I would rather have a game half the length of Portrait of Ruin that is refreshing to look at over Portrait of Ruin. As a fan I remember starting to get really pissed off about it when Portrait of Ruin came out.
Considering Portrait of Ruin was only about a 4-5 hour game, I'd rather have that than a prettier 2 1/2 hour game. Mind you, despite the weird clunky partner system, I rather enjoyed the game. I've played enough JRPGs to not mind the art, despite not really liking it (though they got the freakin'
SWORD OF ETHERIA ARTIST to do artwork for Dawn of Sorrow. Couldn't they have used that artist to do the in-game art, too?).
That being said, there are plenty of games that employ nicer graphics that Castlevania could have looked to. But I think the issue was that they COULDN'T do a radical graphics change. After all, IGA had to release one of these every year, and as far as I know, his budget wasn't very high (at least not as high as SotN's budget).
Back to the main matter, I'm not sure about 2.5D. If DXC wasn't as good as RoB (from reviews which I've read, it isn't) and MoF didn't work maybe 3d was not supposed to be the next step. Maybe the next step was an 8/ 16 bit SOTN with contemporary CV moves and spells and actual pitfalls, or an LOI style stage-by-stage classic with 8/ 16 bit sound effects. I don't know, but trying would be a good start.
2.5D
could work, assuming it's done properly. After all, Nintendo does a pretty damn good job with their 2.5D Mario games. If Konami was willing to just apply a bit more money and a longer timeframe to CV development, I'm sure the 2.5D could work out.
For the record, I preferred DXC to the original Rondo. Game felt more smooth to me, and Stage 5' was overall better.
The only game that specifically springs to mind that specifically has reinvented itself evolving graphically and so distinctively so over the years is The Legend of Zelda. Interestingly enough with the release of TPHD, it's supposed to be a "graphical evolution" from TP, yet they've removed much of the bloom lighting and ambience that gave the game its atmosphere in the first place. It's new "clean" appearance just leave it looking slightly more textured but a bit more dull imo.
I'd say Wind Waker -> Wind Waker HD was a graphical evolution, of sorts. Or rather, it evolved the style that Wind Waker employed. The lighting, for example, was top-notch, and the game felt alive. Kind of like a picture-book. Twilight Princess -> Twilight Princess HD just looks like someone playing the game on a Dolphin emulator.