[Autumn]

Personally, As a kensei, Crit damage is dog shit.
It's usable on basics, Wazabane or Raijins lightning crits.
I'd rather get a +1 to its base damage than a 10% crit damage boost, Crit damage only helps lightning types or basic types.

Critical Damage applies to most of the base Class' effects like Sidecut and stuff, which basic attacking is still a good half of a Kensei's kit, while SWA is inherently more valuable, critical damage should still matter to a Kensei, especially since the stat associated gives a ton of hit for them to utilize.

Lightning Criticals don't really gain critical damage from weapons or gear pieces, and is only influenced by lightning ATK actually, same with critical rate, but the point is not purely about Kensei either since finesse encompasses more than just Kensei, to re-iterate, Finesse covers 23 weapons, only 9 of those being katanas, 2 of which already having 125% critical damage.

I do not believe that Raijin is too strong in this current scene, I believe that Finesse is not strong enough by comparison to the elemental scalings, but to say extra critical damage is worthless is not entirely correct either.