I have to agree with what some of the posters are saying here.
If UA distributes J upgrades like cupcakes, it really cheapens the product.
And it really messes you up for potential upgrades (say you are doing a flight you would REALLY like to be upgraded on, you would still not be guaranteed).
Whereas yeah, maybe AC eUps are ...... and annoying, but at least (from my understanding), there are ways to almost guarantee an upgrade on a flight you really wanted.
Also, it's also easy to print on the 1K benefits list (all upgrades, all the time), but if you don't get them cause there are too many 1Ks, how does it differ from the eUp system? At least the eUps give you some kind of 'control' over your upgrade likelihood...