I think that #18 at TOC was improved by "shortening" -- in the form of technology making drives longer and bringing the green into play for more than just Jack Nicklaus with his sweater off. I would like to see the pin on the right edge on Sundays instead of behind the Valley of Sin, that OB sitting right there would make even Tiger's ass pucker up on Sunday if he needed a 2 or 3 there. Plus when guys chicken out and yank it there will be some that'll end up in the Valley of Sin, and I'll bet its even harder to two putt from there to a pin on the right edge. What's that, about 130 feet?
As for #16 TOC, why would it be improved by shortening? Just because that would make it possible to carry the bunkers, and maybe be driveable for a few of the longer hitters. Too much reward, not enough risk. Do we really need a SEVENTH eagleable hole on TOC?
I think some people are looking at this with the viewpoint that making par 5s reachable in two or par 4s reachable in one is inherently good, so any that are "close" could be improved by shortening. It has to be right for it, and I'm not seeing much justification that the holes being proposed are improved by this, there's just an unspoken assumption that creating more options is automatically good. What about variety? If we take this to an extreme we've got a course full of 330 yard par 4s and 530 yard par 5s.
I am intruiged by the idea of shortening par 3s to make them less than full shots. But I don't know what the distance is. 120 yards is an uncomfortable distance for me, its too far for a SW but too short for a PW. But I'll bet there are some people reading this who think 120 yards is just about their favorite distance, as its just a smooth SW, PW, GW whatever.