That's unfortunately a problem WHM had for years ever since AST got added. It has absolutely no defining feature. Starting at level 1 and being the easiest to play isn't a good defining feature nor should being the classic FF poster child healer and the resulting popularity of it be considered as a class being perfectly fine by SE.
Its personal DPS was always lowest the moment everyone got a tiny bit of gear and from then on it was the worst choice for the rest of the expansion, it had nothing special or any reason you'd take it over another healer. And with mitigation playing a bigger role in EW than in ShB, where you could easily get away with playing Diurnal/ WHM it fell even further behind.
AST mitigation is fairly bad compared to SGE and SCH and not enough in a pinch early tier which is why saw practically no AST/ WHM clears unless you really have an outstanding group that mitigates the hell out of every scratch but it brings better dps and that's its saving grace. It also helps that Yoshi practically announced that you shouldn't even think about taking two shield healers.
So we have AST + SGE/ SCH as the meta, with AST/ SCH winning for dps - as always and the 2min burst meta made it even worse. Definitely doesn't get one bit tiring, nope.

I wonder what would have happened if Yoshi hadn't openly discouraged taking two shield healers into content.
Considering SGE/ SCH even beats AST/ SCH on a few fights at the top end, it probably wouldn't be a considered a meme comp that you just take if nothing else is available and real competition for AST/ SCH, leaving WHM in the dust even more. Because the fact that PFs and statics usually lock to shield/ pure combination definitely helps WHM getting a spot but at this point it's like the participation trophy phys ranged get for providing the 5% bonus.
I really wish they'd stop treating participating trophies that barely keeps a class/ role afloat as functioning class design.