The crit down isn't that affecting archers actually. What I really like about current Dimensional Gate event is that Eliza will stun every single party members if she is attack triggered too many times (even when she's disabled by CC effect).
Anyway, back at talent tree feedback thread I made a suggestion about imparting more use to the defending command.
Mystic: Reduce skill cooldown when defending (Talent tree Fortification skill may improve the reduce cooldown effect)
Guardian: Cast misdirection on self while defending
Healer: same as Mystic, but Talent tree does not improve the reduce cooldown
Shadow: gain 15% dodge while defending (Talent tree may improve dodge chance)
Champion: gain 15% reflect damage while defending.(Talent tree may improve reflect damage rate. Paladins will still have best reflect damage rate.)
Archer: gain stealth while defending.
All the additions shouldn't affect arena so much as you'd want all members to do another act instead of defending. What do you guys think?
Otherwise, I think limiting a trigger type character to be only able to activate their aura once or twice per turn will suffice to make every other heroes that has good persistence aura, slower dps capability, and non-dps alike to see some use, as well as adding more strategic value to the game instead of just building trigger team, attack once, see them trigger like crazy until boss die, repeat the attack if boss has not die from first barrage.
Or just apply the current dimensional gate boss' auto stun after several attack trigger to all big bosses in the future.

(though I suppose that'll felt like some lazy but quick fix)