Concerning the value of Tich trinket, I have a doubt about the Leech stat. As stated, Leech works from our dmg AND our heal, you are healed for X% from the dmg and/or heal you do.
So shouldn't also our self-heal done from all abilities turn as Leech heals back to us? Because if this is the case, we are undervaluing leech stat and consequently the Tich trinket.
With Legion? Absolutely yes. But they weren't always. We had some pretty decent choices back in MoP and earlier.
Not really. I remember having this discussion with people just the over day and decided to actually browse through all the dungeons of old to find instances where I actually used tank trinkets, and the times were incredibly small.
Warlords - Rarely. Some of the on use mastery trinkets in Highmaul were actually decent, but they were primarily used for DPS anyway. When BRF came out it was all about DPS trinkets in there too. Blast furnace door was terrible in comparison, Hans and Frans had a terrible one, and Blackhands 'tanking' trinket was awful as well. Vial of convulsive shadows was basically BiS while you typically paired it with the strength trinket that had the random mastery proc. The trinket from Tyrant was terrible, the stat stick trinkets were terrible, as was the class trinket. Anzu's was okay, as was warlords unseeing eye, but aside from maybe one encounter when did you actually need defensive trinkets. Anzu's while a tank trinket, offered the best of both worlds because it actually gave you considerable damage as well.
I should clarify before I go on. Some tanking trinkets are good, but generally they typically have to be be pretty DPS oriented. Most of the stat stick tanking trinket or stamina trinkets are absolutely garbage, and they are terrible at giving good defensive trinkets with proper on use effects.
MoP - Pretty much used all DPS trinkets at the start. DMC and the elegon strength trinket, although the 'tanking' one was actually okay. All of the 'tanking' trinkets in ToT were garbage. I pretty much used the primordius trinket, fabled feather and twin's gaze during that time. Finally SoO tank CD trinket was the only worthwhile one, but I say that loosely. You were still better off using the strength amplification trinket and the DPS trinket off of Klaxxi (for snapshots on DoTs with high vengeance at the end of it's duration). The tank CD reduction one wasn't bad, it's effect was just really small and you were for the most part fine with the base duration of abilities. Reducing the CD of AMS by another 6-8 seconds wasn't really that important, especially when you lost considerable amount of DPS.
Cataclysm - This expansion was interesting because it had a couple decent tank trinkets, but it was also in an era (at least early) where hit and expertise was important for tanks still. Your interrupts could still miss, so seeking out stats like this was pretty important. Still BoT offered 0 good tank trinkets, and BWD had one good tank trinket. I generally shy away from stamina trinkets, but when you have a stamina trinket that activates at a low health threshold and has a short ICD, it's actually valuable. Symbiotic worm is a good example of a decently designed tank trinket. Firelands had 0 good tank trinkets. Some of the tank trinkets in DS weren't bad, but they are plagued with problems that Blizzard still puts on shitty trinkets today. Having a super high health threshold in addition to a long CD, or a random proc that is substantial, but has a near 2 min ICD.
Take note that Cataclysm actually did introduce two very good tank trinkets, although I will say that one of them really isn't so much a tank trinket as it was a trinket that a lot of people used. The Baradin Hold rep trinket basically was a 1 min CD on use trinket that lasted 10 seconds and effectively gave you a 40 or 50% DR to all magic schools. That thing was awesome, and I remember non-tanks using it in PvP in addition to some encounters. The other trinket was a dodge trinket with a 90 second on use effect that absorbed a giant amount of damage and staggered it over a short duration. This was a vendor trinket, and while it wasn't insanely useful in DS (when it became available) I do remember using it on Heroic Madness because it was pretty strong for soaking tentacles as a DK.
Blizzard really is awful at making tank trinkets. They fall into two traps, especially in an era where I'd suggest that tank DPS does matter. They are either completely defensive in nature which means zero DPS, or in the case that they are completely defensive in nature they fail to do anything positive that you would even want to use them in the first place. Personally as a tank I don't like random, I like control. Random procs are awful, long ICD are awful and Blizzard really likes to historically put these on the same trinkets. The other culprit is significant procs that are tied to falling below a certain health threshold. These are decent trinkets, but normally they have long ass ICDs or have a really stupid health threshold to where the proc is kinda wasted (personally, if it's not 35% or lower, it's pretty wasted).
As such to me I like tanking trinkets that are either static in nature (stat sticks) or a great on use effect (like the two I mentioned on vendors in Cata) . The only other type that's really acceptable to me are moderate to small bonus stat trinkets that proc at a certain health threshold, under the caveat that said health threshold is low, and the ICD on the proc happening is fairly frequent.
I could go further looking at tank trinkets, but I don't think talking about vanilla/TBC when DKs didn't exist would be productive. I could delve into WoTLK, but this was also at a point in time where tank DPS didn't matter as much still, and they have changed itemization around so much when I go back and try to think about what I used that I can't really remember what was even good. I will say however, that overall, tanking trinkets have at least been terrible from Cataclysm all the way through Legion.
To another post, there just is no way that you can really justify the Tichondrius trinket, it's just bad. You would be better off with literally anything else of equal iLvL, and honestly you would be better off with something that is probably 15-20 iLvLs lower. The leech effect is just weak and you will barely notice it on any encounters in there. The only way they make that thing good is if it became a stat stick, and the leech itemization was considered 'free'. Then it would be good.