High level play gets stale really fast.
The content required is so specific since only epic god / planar / world ending stuff challenges you. A BG campaign could go there but hopefully not in the first game. It takes two long games or a trilogy to map out an entire adventuring career from 1 to 20.
And D&D always plays best around 5-12. PCs who are powerful enough to destroy entire cities single handedly are a bit ridiculous and problematic for creating credible worlds. When video games start spamming giants and dragons at you at every turn just for challenging encounters the credibility is leaving the building.
