I think it does matter whether its a par 4 or par 5. One can argue the number, 4 or 5 doesn't matter, but what does matter is where the tees are set up as a par 4 or a par 5.
Look at 18 at Chambers Bay. Jordan Spieth hated it as a par 4. The USGA was planning on making it a par 4 for the final round but last minute they decided to make it a par 5. I think that was a very wise decision because the hole is a much better par 5. We saw Spieth hit an awesome 3 wood to 15 feet and we saw DJ rip driver and 5 iron to 15 feet. I think the finish would have been much worse if it played as a par 4.
I completely agree with Jim Sullivan; every golfer is trying to achieve a goal and an easy to define goal is a par or a birdie on a hole. I also think there could be asterisks next to holes when they don't play to their true par. I know there is another topic on for this, but for the pros, the 1st hole at Riviera is not a true par 5. I think the fact that it is listed as a par 5 for the LA Open takes the discussion away from the characteristics of the hole and more to a discussion about technology and how its not really a par 5 anymore.
Your memory of Chambers Bay is a bit faulty. Spieth didn't like the hole "as a par 4" not because of the par, but because there was a bunker that would restrict his drive, that Dustin Johnson could easily drive past. Jordan convinced them to move the tees back to where he didn't have to lay up, and Dustin had to squeeze a perfect drive through the narrow spot [which he did].
That's my problem with Jim's point. It's got nothing to do with the par. The fact is, playing a hole at 480 yards is going to give some players a relative advantage -- it favors the 270-yard hitter over the 250-yard hitter -- while moving back to 525 yards favors other guys -- the 300-yard hitter over the 270-guy.
I do understand that part of the deal is just the psychology of par, the fact that lots of players would rather be making birdie or par, instead of par or bogey. When I have built in-between holes, I used to always opt to call them par-4's instead of par-5's, just to make the course seem harder, because my courses tend to be criticized for being "short". Nowadays, I'm more likely to let the same hole be called a par-5, so that more people are happy with the outcome. But trying to do both is silly, because as I explained above, that's not what I think the really good players are concerned with.