First, and of great importance, Broadie's research shows that the idea of "long and wild" is pretty much a myth.
Yes. As players get better, they tend to get straighter. Because they tend to be better.
There are a LOT of myths that a lot of golfers believe, or that have a hold on them, and this is one of them. Generally speaking, people don't really understand how statistics or probabilities work. They miss a putt from 20 feet, they see it as a missed putt, not as a missed tenth of a shot.
I think the point here is that as you hit it further, the likelihood is that you are hitting it further because you have squarer contact. It's hard to hit it far with a glancing blow. Squarer contact corresponds with straighter shots. Then furthermore, the actions that increase clubhead speed for the most part also correspond with more efficient and therefore more repeatable motions. So longer players tend to hit it straighter.
Personally I think there is a certain amount of self-fulfilling prophecy to this though. If you look at PGA Tour players, the ones who hit it far have to be hitting it reasonably straight or they wouldn't be on the PGA Tour. There is very little correlation between the PGA Tour and the World Long Driving championships. Those guys hit it way further than PGA Tour players and a lot of them struggle to get more than 1 or 2 shots in the grid out of 8. The grid is 60 yards wide, so far wider than a PGA Tour fairway would typically be.
If you can hit it 320 in the air and straight with it, there's a very good chance we have all heard of you. If you hit it 380 in the air and can only hit 20% of your fairways, there's a very good chance we have not heard of you, unless we happen to be long drive followers. Bottom line IMO is if you're designing your course with the PGA Tour in mind, you are designing it with the needs of maybe 5,000 people worldwide in mind (touring professionals worldwide, plus college kids and high level amateurs who have WAGR rankings). The other millions who play the game will be approaching it differently. From +2 amateurs to people who can't break 110.
Erik - thank you for sharing that tweet about the standard deviations. I'd love to know if that changes much when looked at over a week rather than a round. I've love to know if people have hot weeks putting or with their long games or if it's just round to round (which would suggest it was more random). I would guess that putting is more random (so over a week the std would come down a little bit), but long game players have something which clicks before they start the week and hangs around (so over a week the std would still be around the same). I'm surprised that the putting standard deviation isn't higher.