Handhelds play an invaluable role in the current market. They're preserving styles of design that are mostly gone from home consoles. There are many fantastic games, both 2D and 3D, on the current handhelds that feel like they could've fit right in with the best games of the PS1 and N64. These types of games would almost never be developed for the home consoles, and if they were, they'd certainly have to be different (or perhaps sold as a cheap digital release that the developer couldn't profit on). I think a lot of games are handheld exclusive because that's the only place they could be, to be honest, and I'm very glad the handhelds exist to give developers this outlet. Personally, I'm enjoying the libraries of the DS and PSP more than any of the current home consoles. If you like 90s gaming, they're great.