Been thinking, there could still be a backstab talent that feels non-mandatory. Idea:
Hollower: Weapon modifiers and skills that can backstab and apply status effects ignore armor resist when backstabbing.
This would make weapons like Kniles' daggers which can mute a bit more useful. Would need more backstabbing skills that can apply statuses to make this especially useful, but it's a more niche benefit to backstabbing than a mandatory talent.
Or something like:
Magekiller: Backstabs have a 15-30% chance to mute (perhaps piercing magic armor).
Obviously this would incentive always going for mages first, rather than rangers or other characters. Doesn't really change basic strategy or have enough cool factor for my taste though.