I agree about dumping the more gimmicky crap like the Titans, QTEs, shimmying, and arena combat.
There should be more solid, thoughtful platforming, and definitely take ques from what the earlier 3D titles did right.
Above all they need to be more creative and not rely on every gimmick that every other game tried.
I think they should try to weave a few Castlevania stories for a while before going back to the Satan thing. I never really liked the Satan angle to begin with. Hell I don't even like that they used the name Satan. If they are trying to refer to God's adversary they should have called him Lucifer. Satan is a completely different character in the bible. But at any rate, they didn't really need to involve Satanifer in it. They could have left Zobek as the sole manipulator who eventually becomes one with Death and eventually is enslaved by Gabeula after his fall from grace. Right now there's too much sympathy for Gabeula for him to be an effective ultimate evil for the Belmonts to face. The main thing with Drac's character is his hatred of God. Gabe doesn't seem to really have that at all. In short, screw Kojima and his convoluted stories. There's nothing wrong with a more straight forward tale with just a few twists.
I suppose this is the main thing I disliked about LoS: the story. Don't get me wrong, I didn't mind certain parts but the entire thing with Satan and the way it was handled--it had more of a Dante's Inferno storyline nod with slight varivation on how the hero got from point A to point B, but the core elements are still the same in the end (which is already arguably bad considering the gameplay seemed to borrow aspects from other great 3D titles instead of trying to branch out and try it's own thing.) Then there was the entire thing with Gabe being Dracula...I don't mind him being sympathetic (that's what I liked about Mathias and his hatred of God at feeling betrayed) but honestly, he seems to have absolutely no edge to him as an evil Dark Lord at all. I didn't get the vibe at all, not even when he was presented in modern day New York (and I'll openly admit, I'm not a big fan of that either. Not that it's in modern time but that Satan is seemingly becoming the new main bad guy and Dracula is some tragic hero instead of a tragic individual that became an evil bastard) ...I wasn't a fan of it.
Coupled with, as I mentioned, game play/gimmicks from other popular 3d titles, by the end, it felt more like something reminiscent to Castlevania by name and few mentionable things, such as names (and even then, it was a strong departure from any past portrayal from said characters) from past games slightly shoehorned in for the sake of things, which was why I wasn't too fond of the game.
I wouldn't mind a change to Dracula's lore from what's been established--I like the fallen knight with a grudge against God just as much as an evil tyrant of a war lord that makes a deal with the devil, as long as it's done well and as long as the core concept of him being a truly evil, even horrific threat that needs to be vanished for the sake of all humanity is still intact, which, silly story or not, the past CV games have tried to convey in one way or another, in every game where he is the primary villain. I don't need an older CV game in 3D: I don't mind change, I don't mind the series evolving. I just want a game that would literally incorporate various elements, both gameplay and storyline wise, from the previous games, weaving what works together, and adding new elements to add a flourish, which is what I feel like in large part, LoS really didn't do. (Though it did have some good ideas.)
Personally, I rather like your idea Renonsgoods.