I think this pattern you're noticing is actually symptomatic of the companies organization, i.e. how they structure their teams, and what those teams do.
Just about every example you listed (except Elise) were reworked, and subsequently nerfed in numbers. Here's the process that Riot goes through such that the pattern you're noticing occurs.
Riot has a reworking team, and a champion team. Both of these teams create what is fundamentally new abilities through reworks or new champions. Not once has a champion been released, or a champion reworked, to have an ability of theirs fundamentally changed shortly after (to my knowledge). This is because the Champion and GU (gameplay update) teams don't stick around much with the champion after they're finished. They finish the champion, and they move on.
So, if certain abilities happen to be fundamentally overpowered by nature of design, the guys who nerf those abilities are the Live Balance team. These guys don't change abilities, and they don't revert fundamental changes to kits (i.e. reverting new abilities to old ones). They mostly deal in nerfing numbers, and perhaps scraping off excess strength that one ability might have (a good example of this is Kassadin's Q silence; the silence was removed, but the core identity of his Q didn't change much).
Usually, if a champion is a miss instead of a hit, it takes months or even years (hello, Aatrox) for that champion to see actual gameplay updates (new abilities, or entirely reworked abilities). I agree with you that this is a problem, and I think there's a fairly simple solution.
I think that the GU and Champion Creation teams should stick around with their work after it's been released. They shouldn't be so hesitant to change these champions after they've been released, because often changing these broken abilities into balanced abilities is better for game health. So why don't they do this?
A big reason, I think, is that champions and their kits directly tie into Riot's income source. Zoe might have a really broken CC ability, but changing that one week after release might be a huge hit to her sales, purely because it's been changed. This could also cause a huge backlash, because one player might examine the release kit of Zoe, and decide to buy her with RP; only to find that one week later, her kit has changed in some way that he didn't like, and so now he regrets buying the champion with RP, and might furthermore complain about it.
By admission, this doesn't apply as much to GU champions, as a significant portion of players might already own the champion who's been reworked, but it still counts, even a little.
Another reason why they might not change these champions fundamentally after release is because it's risky. There's no guarantee that number changes won't solve the problem, and adding new abilities into the game, or entirely reworked ones, is always a balancing issue. They could just as easily make a champion worse, especially if they jump the gun only a week, or even only a month into a champion release.