how about this then...
the 'evolution' of gaming is kind of like leveling up in a traditional rpg. the first few levels come by pretty quickly and offer significant gains, at the time. we're at a point now where the hardware is starting do more than we planned to require from it. the first steps in the evolution was limited by the lack of available hardware. it's not that duke nukem 3d didn't really want to be a 3d game, it's just that 2.5d was still where it was at for the vast majority of pcs back in '96.
as for your last line
http://www.borderlandsthegame.com/