Probably because Fallout 3 had a stuff ton more story line and actually had effort put into its graphics engine.
Irrevelant.
I think they'd still complain about the lack of real story line and over-doing the whole Duke thing.
It's a loving Duke Nukem game, it never had a story. It's just a mesh of your classic 80's action heroes all into one person. It's a satirical game.
Everyone was expecting it to be really great because it was THE Duke Nukem, however it didn't live up to it's hype at all.
There were the numerous engine changes then 3d realms had to start from scratch with each change, there was a low budget, a staff of less than 10 employees and a law suit that went on for years and 3d Realms went bankrupt. What do you expect? With all these loving problems I didn't set the bar too high for this game and I am enjoying it for what it is.