Dawn of Sorrow is the business. Any others like that? I didn't like Portrait of Ruin nearly as much.
So lawyers, bugs and ads. The first one's unavoidable. I get that one.
The second is honestly not that common. People are playing these games for free with emulators on PC Wii and DS. The only bugs come with unique games that take advantage of quirks in the hardware like Starfox. If someone hasn't written a nearly perfect emulator for old consoles, I'm a fingerless glove.
I rarely see any kind of promotion for virtual console titles apart from the weekly lists from destructoid/joystiq et al. It's only when they add something, e.g. HD remakes or online play, that I see any advertising going on. Generally that's not much bigger than a spot on the PS3 store's main menu or marquee.
Yup. You hit it on the nose.
It's true that these games can be played on emulators but even with that emulation software, someone, somewhere down the line has to get paid for letting a company use that software, so it all comes back again to the legal aspect.
Additionally, there are just some emulation software programs that are still a bit buggy even in 'perfect emulation' that companies just don't want to deal with.
Another slant I would like to add would be the devalorization of the original game titles. Besides extra costs (as mentioned previously) sometimes companies don't want to 'cheapen' their game software title experiences by making their titles available at each and every avenue possible. Releasing it on all platforms makes it accessible to everyone but that also takes away the 'thrill of the hunt' by not keeping it exclusive to a specific system.
Take for example Atari games. They've released their vintage Atari 2600 titles on almost every platform imaginable. Once people buy these games for whatever platform, they play it, feel nostalgic then put it away right before telling everybody how awesome/cool it was to play the game again but now they don't need to play it again for another few years/decades, etc. . Once that cycle has run its course, Atari waits another year or two to re-release the same titles across all new platforms or on the same previous platforms, but with small tweaks to the software or interface (i.e.; maybe everything is now controlled by a stylus pen as opposed to being strictly control pad only, etc.) all while the people who purchased the same titles one or two years prior simply look at Atari and go "WTF? They're releasing the same game again?".
There's also the possibility of the game companies not wanting to deal with porting games because they will take too long and the money/effort put into the project will not lead to a profit.
Personally, I'd love to see a huge Castlevania GBA/DS compilation on a current gen handheld or even a home console but the reality is that Konami does not want to bother with it and they want the fans to clamor for the original titles. If it is released (unlikely) which system is it going to be released on? How much will it be? How are the royalties for licensing the previous titles going to be handled?
In a perfect world, nothing good would end and nothing bad will ever happen. Unfortunately, this world we live in is far from perfect and I'm afraid will never be perfect.
So in the end, we can only wish that Konami takes the initiative and makes a compilation happen. If they do, I'll buy it.... for $19.99 or less.