I watched the new Dune movie yesterday and it just made me realise how absolutely hollow cosmic DC is these days and how badly screwed up the whole 21st century UP thing was.
Something like that, a major political action that ought to change the way the entire known universe works, should have been allotted more time and weight than it was.
Just look at what it took to found the UN in the real world and how long it took that to actually become somewhat functional (and how flawed it still is). The UN was founded after WWII. After the League of Nations was founded in 1920 and dissolved in 1946 for failing to prevent WWII. Two horrific wars, and it's still partially held together by mutually assured destruction. And this is on one planet, imagine that on a intergalactic scale. That is not something you accomplish in less than a week by being inspirational and causing time loops.
They tried to make Rogal-Zar a unifying event/factor, but it did not feel believable at all. It wasn't big enough, not the kind of wake-up call that makes the entire universe stop in its track.
In a world with well-written comics we'd also have seen a lot more opposition and conflict in general. How do you get the violently patriarchal Psions under the same umbrella as matriarchal Talok? How do you deal with the Dominion, who are both powerful enough that you have to deal with them and outwardly violent enough that you can't just let them be normal members?
How does a group like that deal with outside forces like the various lantern corps, Darkstars and L.E.G.I.O.N, who hold a lot more power than most planets? Hell, probably a lot more power than the UP itself, which makes them look weak and kinda useless. Oa are kind of just going along with things in the comics, but they would under normal circumstances just be able to steamroll anything the UP says or does.
L.E.G.I.O.N. alone protects many planets (I think R.E.B.E.L.S. had it at a couple of hundred different ones) and holds both political and financial power, and aside from not being very cooperative in general they'd probably be totally opposed to working with an organisation that is associated with the Dominion. And they can use their power as leverage. Join the UP, lose your protection. Can the UP make up for that?