Is it an obsession with length or an obsession with course rating? Maybe those in the design business can comment, but it sure seems to me like a lot of courses get built where the developer doesn't care about the architecture, only that it is perceived as a "championship" course. Par 70 won't do, neither will a course rating of less than at least 73, and I wouldn't be surprised if some don't place ending up with a 75 from the tips as a requirement.
Because the way course rating seems to be calculated is almost wholly dependant on length, you don't have much room for a clever 120 yard par 3 or 350 yard par 4 -- at best you can have two or three such holes. If you have more, then you'll end up with a terrible slog through a series of 475 yard par 4s and 635 yard par 5s to make up for them and keep the course rating up.
The funny thing is, almost every average (and a lot of better) golfers think that slope is the indication of difficulty, so merely pumping up from the slope from the back tees (while leaving it reasonable from the regular tees) would be sufficient to make people BELIEVE they are playing a championship layout. Ask about any golfer what the toughest course they've ever played is, and they'll start talking slope! And they'll quote the slope from the tips even if they played two sets up. It isn't as if those courses really are going to host US Open qualifiers, so a par 72 with a course rating of 71.6 and a slope of 147 will be seen as far more difficult by 97% of golfers than one with a course rating of 74.5 and a slope of 131.
Not like its hard to pump up the slope of a course from the tips while leaving it reasonable from the regular tees, just move the tees off laterally and require a 240 yard forced carry on a few holes. And note that on the scorecard and with a sign on the first tee, to scare people who aren't up to it from even trying the tips. Not that I advocate this as a reasonable course of action, but if you are going to design to stupid requirements, I think that's a better choice than having a lot of really long par 4s and 5s that don't have much interesting going on with them because length was the goal (and too many long holes that are also hard probably won't bring too many people back for another round)
I guess one danger is that a lot of golfers seem to choose the tees they think they should play on an unfamiliar course based on the distance listed on the card. "Hmmm, 6100 yards, that's about what the tees I play back home at Frozen Tundra CC are, I'll play these", ignoring that the course conditions, rating, slope, etc. can be quite varied even if the yardages match.