I'd just like to point out the futility of arguing with Trizz about the merits of Gangplank. I doubt any sane person has played half the amount of games as Gangplank as he has, so trust his opinion to be more accurate than speculation and theorycraft. I know I do.
Also, I support the idea that Irelia is overpowered. She doesn't even really need damage items, you can build her as a tank and become tanky dps with built-in life steal. You can build her as an AP character that can become an AP carry, and you can build her into a DPS nightmare by actually buying damage items with her. Irelia was actually more or less fine after release, barring some tweaks, but then (like Caitlyn) they have been buffing her for no reason ever since.