I hope I'm not the friend you're referring to Agent.
Regarding 2D & 3D, I like to make a few comparisons.
One would be Mariokart on the SNES, compared to Mariokart 64. I enjoyed the game play of the original SNES version much more than the 3D sequels. I played the wii one the other day, but couldn't get into it, unlike the SNES one, which I'd happily sit down and play right now.
But to compare say, Super Mario Bros, to Mario 64, I consider these to be two completely different games. One is not better than the other. They are different. I enjoy them both differently.
Then, as a final example, F-Zero on the SNES compared to F-Zero on the 64, then the Gamecube. That is a very interesting evolution, making the transition from 2D racing into a VERY 3D racing on the N64 version (remember the cylindrical tracks in the 64 version, I used to get so dizzy on them!), only to add a tonne of shiny onto the Gamecube release (although I hated the casino levels as they seemed so out of place!).
What I'm getting at, is that a game is a game. An idea could work in both 2D & 3D, just how the same idea could also fail in 2D & 3D.