Just out of curiosity, what games to people believe have lost their way from their original intended audience?
In my opinion, some of the biggest culprits are:
Mass Effect (went from RPG to action)
Dead Space (went from Survival Horror to action)
Final Fantasy (went from open-RPG to linear-action-RPG)
Resident Evil (went from survival horror to action)
These game developers tend to ignore the audiences that make their games popular in favor of the wider audience, which often removes all the features that made the original games worth note in the first place.
That's not to say the sequels are never enjoyable, but game developers seem to lose respect for what made the originals so good.