Well you already have 10% from light armor already. So they do not need to put even more spell crit on light armor.Dual wield daggers with the twin blade and blunt passive gives 10% additional weapon critical.
You can get an extra 6% critical if using a bow.
Two handed doesnt have any critical bonuses, but you have raw damage boosts with arcane warrior and momentum that make up the difference.
I play a melee dw nightblade on one faction, and a caster templar on another. Both are pretty similar in the overall levels of critical they can get.
My nightblade gets 21% from medium armor, 10% from dual daggers, 5% from thief stone, 5% from 5 piece night's silence, and at the moment 6% from precise traits on my weapons and 6% from being a khajiit. That's 53% melee critical overall.
My templar gets 10% from prodigy (light armor), 5% from thief stone, 20% from inner light (which takes up a hotbar slot, and i hate that about it), 5% from twilight's embrace 5 piece, 5% from willow's path 3 piece, and 6% from precise trait on my resto staff. Total comes out to 51% spell critical.
Really the big difference here is that a spellcaster has to sacrafice a skill bar slot for their big critical buff (inner light), while a melee character doesnt, and gets an extra 3 piece bonus open. At the moment my nightblade is using the 3 piece night mother's set, which reduces enemy armor by 20% whenever i get a critical, synergizes well with all the crit chance.
Personally, I wish they'd get rid of the crit bonus on inner light/magelight and put it into light armor passives so I'd stop having to waste on of my precious 5 skill slots on it.