Agreed, IMHO SE should try to go back to having 1 or 2 gimmick fights per tier.
They've had some flops for sure, but then these gimmick fights have also spawned some absolute classics IMO;
Solo healing Ratfinx on AST whilst also handling potion and bomb duty to pad my cohealer's damage ranks as maybe one of the most enjoyable raids I've ever done in this game. Every last GCD counted, the pinnacle of being a busy healer IMO.
Meanwhile farming Lamebrix with the static all trying their hardest to murder each other with traps was a highlight of the tier. If you've got a static that's never run it, go try it, it's not a hard fight and honestly that's a good thing as it gives the group plenty of headroom to have fun++
Lastly, Chadernook was a good demonstration that gimmick fights don't need to be memes to be good, it was a great fight with a solid gimmick. It had tons of room for optimisation, it had teeth and would merrily eat tanks but wasn't so unforgiving as to be annoying.
Personally, I'd merrily sit through a few more Catastrophies if it meant the chance of tiers with fights as fun as the above. Anything to help mix up the recipe and get things feeling fresh again.