I think a lot of it is Shadowbringers overtaking Heavensward as many people's favourite expansion during that time.

I still think the "just get through ARR" bit is true to some extent, and you can notice the increase in production value each expansion if nothing else. Stormblood is where the shackles of the PS3 were finally broken for example, so it does have that going for it.

I personally really enjoyed Heavensward, so if that doesn't hit the spot then I don't know. That's not to say it didn't have slow and/or boring parts, of course (they do tend to pad the runtime), but the overall Dragonsong War story and the Ysayle/Estinien bits were great to me.

Soon people might say the same thing about Stormblood. "Just get to Shadowbringers."

I think people have kind of been saying that since Shadowbringers came out, honestly. Or at least "get through to the patch quests". Stormblood was overly ambitious and tried to tell two stories at once, which resulted in too little screentime for either to really develop and hit home. Also they had to split the writers, so the Heavensward writer only worked on the far-east stuff, and Ala Mhigo ended up being pretty boring and forgettable.