U2 is the best it has ever been in AE 2012. It has increased range, the input is really lenient and it starts up in 1 frame which means it beats true safe jumps100% of the time. It also punishes any move that’s -1 or more on block. Most people tend to assume that any move that is -1 or -2 on block is safe, because the fastest normals and reversals in the game are 3 frames. So unless they’re playing against Gief or Hawk with their instant start ultras, most people will happily throw out pokes, jabs etc. that leave them at -1 or -2. The threat of U2, if your opponent knows the Guy matchup to a high level, can also really change the dynamic of the match. For example, in a Guy mirror match, if you picked U1 and I picked U2, I could neutral safe jump OS you after every hard knockdown. Whereas you could only do that against me until I got my ultra, then you’d have to back off and try something new.
It depends entirely on your opponent. If I were playing Poongko, I would probably use U2 because after watching many of his matches I’ve seen the resets into safe jump mixups that he goes for and those situations are when U2 would be perfect. Also many Cody players tend to go autopilot with their safe jumps sometimes, so I tend to use U2 against most Cody players.
I think what you suggested for U2 having a secondary counter function would be interesting, but it’s too late in the day for them to implement stuff like that now.