Magical dps / Physical dps issues

k so odyns veil was a great item kinda like thornmail but if thornmail existed for abilitty reliant enemy it would break the game but why give thornmail doesnt that break the game just as bad theres way more armor items then magic making magic defense vs leblanc akali etc hard why is magic dmg getting so much help in being op i just think there needs to be more magic resist items or odyns veil in summoners rift just an idea :3.