I heard that Morrowind, a RPG for the XBox 360 is going to take approx 250 hours to complete (without all the secrets). Thats about 4-5 times for an Final Fantasy Game
I think that could be a bit too much, restricted or not. How many people do the developers expect to complete it? Playing any game too much for too long gets boring after a while - so most people will stop somewhere and you've got to have the time to play it as well.
If people are just sensible about what they do (or read the warning notes on games), then there wouldn't be deaths from exhaustion and neglect and they'd be no reason for restricted playing time.