Well... people argue that ISU doesn't want to do it because it would hurt a lot of skaters since basically A LOT of them do this.
I don't know. I think the amount of vitriol against prerotation is in a lot of cases (not all) just an excuse to hate on certain skaters (not necessarily Russian)...
I just want fully-rotated jumps to be rewarded and those skaters constantly getting away with doing 2 or 2.25 rotations on every single triple they attempt (not even factoring the newer quad jumpers) to be penalized accordingly. During the 2013 or 2014 season I was really starting to get on Ashley Wagner's case about her pre-rotating (and under-rotating) the hell out of her 3T in her combos as an example.
For me, it doesn't matter where any skater is from or whether I like their skating PCS-wise or not (see Miyahara, I adore everything about her overall skating). But there are so many other nuances within the rules that are so technical- I don't see why severe pre-rotation shouldn't be treated the same way. I guarantee some skaters are doing triple flips that have MORE rotation off the ice than Uno's quad flips. And that's absolutely insane that he gets the points plus positive GOE's.