I've never actually played SotN and I love both DS games that everyone here hates. If you would just stop comparing the penis sizes of different games to each other and enjoy them for their merits, you'd probably be a happier person.
(I use "you" here in terms of speaking to a group)
But seriously, of all game fanbases I've been too, Castlevania fans seem to bitch the most. I don't see why- plenty of good games have been thrown our way after SotN, just not QUITE as good. That doesn't mean you can't enjoy them.
I don't see it as "bitching" as much as tough love. Us Castlevania fans are very critical of the games in our series, and who wouldn't be given the exceptionally well produced and innovative Symphony of the Night. While we may sound harsh about other games in the series, I doubt that any of us would consider them completely atrocious. Each game, I believe, has a different quality to it, some greater than others; these can be measured by the combination of not only gameplay, but art design, graphical prowess, soundtrack, and many other important features that are combined to craft the CastleVania experience. In my opinion, Symphony of the Night captured this experience better than any other game I have played in the series, and to judge other CV titles by this standard is thus a true necessity.
While it's nice to see the more current titles emulate and add on to the same great gameplay, at times, many of the other properties of the games may be unbalanced when matched against how they play. For instance, Harmony of Dissonance had many inventive locals and artistry, as well as great graphics for a GBA title, but the soundtrack was quite not up to snuff with other CV games, especially SotN. Portait of Ruin had some nice gameplay with a very well composed soundtrack, but the style of the graphics and art, particularly its repetition and unfortunately ill-produced and obvious Anime design was not up to the same caliber as Cv's flagship title, SotN.
Do these factors mean that these games were bad? Of course not: by no means does a lower amount of polish than the best game in the series means a undependable game. Quite frankly, Portait of Ruin was one of the best games I played on the DS, and Harmony of Dissonance was a fantastic GBA game and definetaly up in my top ten for the system. When we compare a CV title by using SotN as the grand model, it is no different from comparing a Pink Floyd CD with Dark Side of the Moon, or a Metallica album with Master of Puppets. As it stands, comparing new CV titles with SotN is not a absolute hatred of the title, but merely a way of measuring how well it captures the CastleVania experience.