Its been said a few times on here, but I am not certain people would really grab onto the idea of par 75. The mindset of shooting less than 80 is a big deal. Even on a par 69 course, breaking 80 is something a lot of people think about.
Also, I think a lot of well-known designers would shy away from a high par course like this because of how it would be used by the owners. Not as another golf course, but kind of like the "worlds fattest hog" or some other fair attraction, for a given area. Kind of like par 6 holes.
I'd like to play a high-par course, I've never played higher than a 72 I don't think, but it would need to be done right.