Why does heimerdinger have so much HP regen?

For those unaware, Heimerdinger has the highest HP regen at lvl 1, and almost twice the HP regen scaling of anyone else in the game. He goes from 11 – 40.8 HP/5. He already gets 2.2 per second right at the start of the game. This makes him far more punishing to lane against than he already is, as any damage he gets doesn't stick.

I wouldn't be as annoyed if he had a heal or something active, but this is a passive thing. He just inherently regens insanely fast. Riot, please nerf this to give us options to lane against him.