well this is very debatable. You see as irelia you're usually going to stay on their AD/AP carry. Consider this, the dodge% well help you get to them faster. Usually if i focus an AD carry, they're going to be guarded by a support chracter, perhaps taric or soraka. My passive alone is already enough to sustain their CC. If you're up a against a good AD player, for example an ashe who is really good, they're not going to just run away from you, they;re going to try and kite you. the dodge runes could potentially save your life and give you that extra speed boost from Nimbleness. Also, in a teamfight--the other team isnt going to CC you. They're going to CC your carries/supports. This isnt going to effect you. If they do CC you, their insanely dumb. Expecially at a higher elo you're not going to see 3-5 people focus an irelia, its ridiculous. Depending on your team comp you feel confident in your carries to do the job. Imagine this, a team fight starts and you focus the carry, their support follows their carry ensuring that he/she doesn't die. Instantly you made the fight a 4v3 because only you engaged on thei carries---this is a win-win situation for your team. Sorry for the long comment but think of it that way.

Why no merc treads? With 3 enemy champs around you have like 75% cc reduction

This build is amazing!!