I definitely, whole-heartedly, agree that the games really really need to use the full capacity size of the cartridge, at minimum to justify the expense of buying those cartridge at that storage-size price.
However, for Castlevania, I'd rather not have a game which require too much stylus control. One, it's tedious, two, it can cost you your stylus if you're playing it in a busy public place </trauma>. I definitely only want those extra MBs wasted on graphics, game areas, audio, item list etc and not the coding for the touch screen.