1. Almost all of your initial complaints lodged against the metroidvanias (and Rondo, for that matter) revolved around character design. "Belmonts aren't the main characters all the time, and when they are there they don't look the way I want them to!"
Not an entirely accurate portrayal of me, but I can see what you're getting at. Yes, character design is a big deal for me whenever I'm playing a game. One such example is the 3rd Person Bionic Commando game, where Spencer has dreads. For me, it's entirely necessary to buy Rearmed for that classic "Ginger Duke" look. Without it, I'd rank it lower, but because I can fix my biggest gripe with the game, it flies right up as one of my all time favourite games of this generation. As for the "Belmonts not looking the way I want them to" argument, I must protest against that because I have no issue with Julius Belmont. I'd just wish I played through the game as J and not as Soma, and I loved how Julius is given the 8-whip directions from SCV4 in Harmony of Despair. Yes, I know you can unlock Julius after beating the game, but after completing it, I had no drive to play it again, and it was a bummer to feel that way after unlocking him.
But Lords of Shadow doesn't look like the classicvanias either; it's more like modern Forgotten Realms or Jackson's Lord of the Rings art, particularly as far as monster design goes. And don't get me started on censor-cloud Satan. *rolls eyes*
2. I'd argue that the only point at which LoS returned to the 'gothic design' was within Bernhard Castle. I'm not that bothered by it though because it is obvious why they did it that way. However...
The series didn't really have any music resembling anything even remotely 'orchestral' until the SNES/Genesis era and even that is pushing it; it always had catchy tunes that were some mix of techno/rock/jazz/baroque and other styles, the mingling of which resulted in a powerful and unique atmosphere, and to suggest that Shadow's OST is somehow truer to the older games like you did in your opening post is absurd. It did NOT have music in line with the classicvanias AT ALL. Furthermore, staples of the series like hearts, wall meat, etc... were taken out and in their place was crap like the chupacabras. All of these changes resulted in a fundamentally different atmosphere.
As for the Gothic Scenery being absent in LoS, what about the architecture of the villages, and the costume designs of the people you meet? How about the trees in the Forest of Bones? It has an entirely grim and medieval Gothic theme throughout the majority of the game, with a couple pauses like Pan's Temple to add some peaceful ambiance to even things out.
I agree with your chupacabra and lack of hearts and wall meat, but again, this isn't a traditional Castlevania game. LoS is if it took a more fantasy-realism direction. Looking back at the crawlspace before fighting the Butcher, would the atmosphere benefit from Gabriel finding cooked pork hidden in the wall? You still break objects like candles and other furniture for sub-weapons, sure they're not hearts, but the concept from the original is still there.
I will disagree with your discussion regarding the music though. I don't see how guitar/jazz/techno/rock would have improved the game. The LoS soundtrack fit their intended fantasy aesthetic perfectly. If you listen to the SCV4 soundtrack, there are moments in the OST where it's ambient and mood influencing. Some of those tracks are even remade for LoS, such as "Courtyard", the beginning of "Waterfalls of Agharta", and "Belmont's Theme". It had a pacing to it, and I found the "Ogre Battle" music entirely memorable. It's not as forgetful as, let's say, any of the original tracks from Harmony of Dissonance or Lament of Innocence.
3. Only people ignorant of the series would try to argue that the inclusion of locations outside of a castle made it less of a Castlevania game and I find the implication that most metroidvania fans think that to be a little far-fetched. It doesn't help that multiple metroidvanias have places that take place outside the demon castle.
One of the recurring arguments I've read multiple times is "It's called Castlevania. Where's the Castle?" I've seen these come up many times. I know that not everyone has these views, but it's a popular argument for bashing against LoS. I think it's ignorant as well, but then again, non-CV fans say it too. I mean, I can say the same regarding Portrait of Ruin, which also took the player outside of the Gothic castle, one of the levels being a massive pyramid in what looked like Egypt while another appeared more Victorian, and not even LoS went as far as Egypt. MS wanted to make Castlevania seem more like a dark fairytale than remain confined to the more famous Castelvania trademarks. It was a gamble, but for a 20+ hour long game, it's necessary to have variety in the environments. What about the entirety of Simon's Quest, that took place entirely outside with towns and open forests/lakes? How about Castlevania 3, where half the game isn't even set in Dracula's Castle? You didn't even get inside the castle courtyard until after stage 6. So yeah, it's kind of a bad thing to say going against LoS. Sigh.
4. I hate the complete and utter absence of multiple staples of the series that have been in Castlevania since the first game in the series was released, and then see people saying that LoS is 'the Castlevania they grew up with.' I hate that the LoS-verse story-line is obviously comprised of re-hashed plotlines and mushed-together characters from the old canon (mostly the metroidvanias) and then fans of LoS whine about the old canon's story and characters and LoS' creators belittle previous installments in every other article I read. I hate that people claim that LoS is more like the classicvania games when it plays far more like the steroid-addicted love-child of Lament of Innocence and Legacy of Darkness, and contains metroidvania-esque content like fairies, monster steeds, puzzles, lame platforming, and I could go on and on...
I hate when LoS fans complain that LoI's motivation of having a 'personal grudge' against Dracula is insufficient when the same exact argument could be made against LoS because the motivations are incredibly similar. But most of all I hate that all of the changes made in LoS culminated in a fundamental alteration of the atmosphere of the series. I am hoping that Mirror of Fate will fix that at least to an extent.
Simply by saying that you hate LoS could have sufficed. Saying it like this makes you seem a bit spiteful. I don't see how the LoS story is made up of rehashing old plotlines. I mean, having to re-open the heavens by using forbidden supernatural powers with an ongoing dread of the apocalypse or "the end of days" lingering in society is kinda complex. It's nothing like the far more simpler "Dracula's Back, Kill Him" plotlines. I know that's wrong of me to say, as I know there's complexity in the original timeline in itself. And it doesn't really do any damage bringing in some nods to the other games, such as naming one of the vampires Brauner, or having the Werewolf Boss named Cornell.
For someone that claims to be neutral towards it, you certainly have a lot of hate for the game.
Now I will say that I wish more metroidvanias had focused on the Belmonts and had better level design, and that the original canon could REALLY benefit from being completely re-written and re-released in some sort of ultimate collection to iron out all the weird stuff within, but to say that you're 'betrayed' when the overall story is wonky and whenever whip-wielding Belmont isn't the main character of a series with well over 20 games that span over 1000 years that has a psychotic vampire that wants to kill everyone that were produced over 25 years and handled by multiple people during those years and you don't expect anyone outside of the Belmonts to take note-worthy initiative against said psychotic vampire in all that time is just... expecting too much.
It is expecting a bit. You're right, 27 games with 1000 years of plot is a lot of time for a lot of different characters, but out of those 27 games, there were only 4 games that featured Belmonts as the main playable character after SOTN, and that was more than ten years ago. Before SOTN, nearly every game had a Belmont, so to see Gabriel Belmont in LoS as the main protagonist... it's refreshing.