I'm reasonably sure that high IQ (i.e. over 140) is not particularly well correlated with outstanding achievement. I am almost certain that extremely high IQ's are not a prerequisite for extraordinary achievement, though there may be some specific fields where this does not hold true (say, theoretical physics).

I remember reading that the optimal IQ for success in life is actually about 130, but can't find a source for that now. I did find this though, which seems to support your claim.

I think that having the general population's IQ raised would have such wide-ranging effects that looking at society as it is now isn't a very good indicator of what that would be like. Society as it is now isn't set up to support people with very high IQs (or even get the most out of the IQs that people have to begin with), so I'm pretty sure there would be changes to all kinds of things to fix that.