The problem with trinkets is that anyone can use them, there aren't very many of them, and the ones that are any good are even fewer. Therefore, even if they have an even droprate with other items, they still end up being fought over. Dragonspine Trophy in particular is a very poignant example because of the raw impact it has on your character. Any class that uses physical attacks wants it -- some deserve it more than others, but who exactly that is seems to always be in debate.
The other issue with trinkets is that you get two of them. The other two slots I would describe with this peculiarity -- neck and back -- you only have one of, so if you can finally get that one elusive necklace or cloak, you're set. But with trinkets, once you get one, you're still stuck with finding a second one. I was using Bladefist's Breadth until I got exalted with BT faction, and even then I'm not sure if it's an upgrade for me or not. (Yes, I had that much trouble even getting abacus or hourglass, and I didn't think the badges were worth it for the brooch.) My second trinket was Mark of Conquest, which I have loved to death because of how anti-consumable I am, so even though it's not the best DPS option, I'd need a good reason to replace it.
____________________________
Only the exceptions can be exceptional.