That's the one thing that I enjoyed about the OT. It took massive amounts of concentration to do things like lift a ship out of a swamp or get flashes of the future. The limitations made them seem more like highly skilled warriors rather than superheroes. And you felt more for the characters when Luke was getting beaten by force-flung crates vs when Obi-Wan dropped ten stories and got up without a scratch.
Then again, I got the impression from Yoda that the limits on the use of force were caused by self-doubt. A well-trained Jedi wouldn't have these limits.