1: I hope we never get to the point of power creep when Aviana+Kun combos are obsolete. The combo is pretty damn nuts, and has a wide variety of uses. You could probably even make a decent C'thun deck around it...
2: Druid pushes a lot of other control an combo decks away from the Wild meta, and makes faster decks which prey on them shine. At some point, I think a changeup is healthy, even in Wild.
Druid pushes other decks away that are not worth being in the meta. Reno decks have significant chance against snything. Im recently playing Dragon Control Arcibishop Priest and I haven't lost a single game agaist Druid yet. It is not like Wild meta is warping around them. Wild meta rn have fair amount of Fast and Mid game decks, Control decks and Combo decks too. The only problematic Aviana+Kun interaction is Star Aligner Druid(Here is my point of view) . Other versions are powerfull but not close to Tier S
I don't see any reason why Star Aligner is better than Togwaggle, the Star Aligner combo require much more combo pieces and you can't even use Oaken Summons because of all the 3-4 mana combo pieces to thin your deck and battle aggro, Togwaggle only need 4 combo pieces and Juicy Psychmelon draw all of them (it's almost impossible to not get the combo by the time you get to 10 mana).
Togwaggle might be slightly weaker to hand disruption cards but the only classes that even run those cards are warlocks and warriors, and even than they must hit togwaggle or have less than 6 cards for the rest of the game.