Two things 1 it's up to the developer to decide if he want to make a 3d game in most cases. AG can just pump out some money to support the project. 2 trust me, most 3d games have lame graphics. It's extremely easier to make good 2d graphics. Think at raze, one of the most realistic game we have. Graphics as good as those in 3d would take ages and ages of work.
The thing is, making a 3-D game in flash, would be near impossible. (as far as I know at least) and since Armor games is a flash gaming site, it would be a bit odd for them to start hosting other games as well.
Making 3-D games would cost a lot of money and also very difficult to make one. The file size would be very large, you have to think about how difficult it would be to play said game and the game could increase the chances of causing epilepsy.
Nah, I like 2D games appearance better. Not kidding. A couple 3D ones are okay, but they are harder to make and aren't worth it when the game is better as a 2D game. For example, imagine This is the Only Level in 3D. Yuck.