If you're talking about a middle screen or a left right or something similar, then you're right. It works because the defense is pushing upfield, creating room and space for the blockers and ball carrier.

In the case of a bubble, the defense that we are talking about is playing either a matchup zone or press. Neither one of these situations is ideal for that play. The defense is already at the line, where no space is present. Your wr's don't get to fein run or pass, because they're getting jammed anyway, and by the time the ball gets out, they've recognized it and they're on your wr. This is all about deception, but you're not able to deceive. You could argue that a pick would work because defenders will chase wr's. The issue there is that the defense is already at the line, recognizing what is going on, and able to fight through the block in read and react mode.

As for your oregon example, refer to the matchup zone. Teams that play oregon go matchup zone and play vanilla because of you guess wrong on your call, then you're screwed. They'll have numbers and you won't, which will create a big play. So say you're in trips and the d is in matchup zone. the play starts and the db's take a step back, as your wr bubbles down, the other cb or lb or s (depending on the set) is waiting for him. There is no pick because nobody is following any of the wr's. They're sitting in their zone. I know that's simplified, but it's the same thing that you do against any other option team. Play vanilla and beat them. If they beat you, tip your cap and play the next play.

Bubbles work when teams play off, like what we play on defense. Space is available to both the wr and the wr's blocking downfield.