Yes, we have awesome mods by awesome modders. But single people, or at best, small teams, cannot solve all of game's problems.
Look at Fallout 3, sure, it is vastly improved by mods, but no one can solve a crappy, inconsistent story almost devoid of choice and consequence and memorable characters. That no mod can solve. That was I think one of the great triumphs of New Vegas, despite its problems, the development time, etc, it managed to have a very good story, awesome characters, and provide a solid framework that could be expanded upon by all the very talented modders in the community, to improve upon an already great RPG.