1. You're assuming we all make a lot of errors while typing. I for one, have short, chubby digits, and i'm fine with the keyboard, as is.
2. I'm pretty sure what we need is more mobile pages over more scrollable.
3. Photos work fine as is. I can see mine just fine, maybe you need glasses?
4. Aside from the fact that draw something is losing people on a regular basis... I would agree that a bigger screen would help with gaming. However, if I really want to play video games, I use a game system or my iPad. My 4s is really only good for quick games on the go.
5. Multitouch works fine on the 3.5" screen, but I understand your point.
6. Like the games, I agree that it would be nicer for a larger screen. However, like games, I move to a better system if I want to watch any real video. The screen size is fine for Youtube.
There is really no good reason to increase the display size, 3.5" is the mobile sweet spot. Increasing the size for a minority of users who want it, would cause too many problems across the board and would be un-Apple like.