That E heal is pathetic and you know it. It's low base, low scaling and in a lot of cases regeneration is going to be more useful than it. Don't give me that shit.
No one said that Cassiopeia was bad for the game. The closest hint to that was along the lines of "and when she's powerful her ability to bully a lane crowd out a lot of other champions from mid lane". If you think that warrants a complete identity destruction and kit perversion, re-evaluate yourself. Re-evaluate everything, because that's a horrifying precedent to set for champion reworks.
Aspect of the Serpent is needlessly complex. Deadly Cadence was really powerful with Cassiopeia's kit; it had one "cause" and one "benefit" so whenever you were using it right it was clearly obvious, you were rewarded for combo'ing it with things like Tear but not punished for trying things like Morellonomicon or Athene's. Yes, it was boring. Yes, it would have been the best place to start to change her - but adding a bunch of random triggers for a bunch of random effects is definitely not what she needed when the skill cap for her skill usage was already considered one of the highest in the game.
25% CDR at some random point in the late-mid-game in exchange for almost doubling her basic's cooldowns? What is actually the point or just handing her a bunch of stats to make up for something you took away just so you could later hand her some CDR? It's so nonsensical. By the time you get the CDR bonus you've already been hurting for 25 or 30 minutes because you don't have the CDR and the worst part is that if you did invest in CDR for your early game like you would want to for laning - that gold is now wasted. By the time you get your cherished piddly sustain, you're almost done laning assuming your opponent wasn't smart enough to just force you out of lane and take your turret because you are actually useless before 50 minutes or so.
Having to wait for the bonus (I refuse to call any of them big, as they are all literally shit rewards) isn't why it feels bad. It feels bad because you're forced to jump through hoops for things that only matter to Cass now because Stashu forced them in.
This whole ordeal has been awful, from the almost non-existent heads up, the utter lack of community input during design, the ignoring of feedback during PBE, to current lack of communication with the community. There is not anything redeemable about anything done to Cass in 4.16. The GU was awful, the TU made her look absurdly cartoonish and the Lore butchery made her a generic Noxus villain. As a player, how the hell are you defending any part of it? You let them set this precedent and they'll start doing it more, and all it will do is lessen the quality of the game.