I know you want to keep it a small time bonus I get it, but make it a little bit stronger?

Like this ... Instead of letting each character getting an trinket make the trinket for the whole account. And make the trinkets evolve like uhm...

Trinket: wizard lvl 1; 12 class attack & 75 health (awarded when player has lvl 30 wizard)
Trinket: wizard lvl 2; 24 class attack & 150 health (awarded when player has lvl 60 wizard)
Trinket: wizard lvl 3; 30 class attack & 200 health (awarded when player has lvl 90 wizard)

Then when you make your warrior/ranger/??? and you have an level 90 wizard in other slot you get a lvl 3 wizard trinket.

Maybe even make/have a few achievements attached to some trinkets.

Digger: +50 health (gained when dig to level 500 in shard quarry)
OOgler: +10 health (gained when waiting in arena without starting a fight)
Musician: +1 all stat (gained when listening to the intro tune for 10 min)