There are probably a few amendments, but it's relatively accurate - trolls just appear to be something of an outlier when compared to orcs, humans and Scourge. Unfortunately, raidwise, it's difficult to accurately say what's "troll-themed" or "troll-centric" outside of the obvious Zul'Gurub and Zul'Aman, which pretty much consisted of troll bosses exclusively.
Everyone will have a different threshold, though.
When the original complaint is that the end game PvE focus is far too much on trolls...
How are 5 mans not relevant?
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I think it's not about the number of bosses but the fact that each expansion contained troll dungeons/raids. I don't think any other race in the game can claim so, not even dragons.
in any case dead or alive zandalar island is still out there with king zul and we will need to deal with it in a future xpac for sure.