I've understood the claims of LSD therapy to be mostly about fixing psychological hang-ups, like the recent research claim that it helps with alcoholism. This is mostly a separate direction from both entertainment and intellectual achievement. Of course psychological well-being can indirectly lead to more intellectual achievement, and an altered psychological outlook can change the set of hypotheses you will entertain as the starting point for intellectual work. No idea whether the post-LSD hypothesis pool will necessarily be better than the pre-LSD one. If it's larger, then it might help discover some unlikely ideas that actually do pan out when you take the time to think through them off-LSD.

Incidentally, there are some interesting anecdotes that deep meditative states achieved by long-term meditators resemble the states you end up on LSD. At least MCTB alludes to this.