Think about it, one trinket gives you more than 50k hp at level 90 but that's all about it.
I have personally never liked them, because using them doesn't make your character stronger tank, but give very good illusion of it. Of course, they have their uses on magic heavy encounters like lei shi, but then again your job is to mitigate the damage you take, and just having more hp won't work. For most tanks, mastery fills this niche well (except for bears which I think needs buffing).
I started to think about this when our tank passed on the tsulong/hc elegon trinkets in favor of brewfest/shadopan trinkets.
What do you think about them?