What makes midlane so popular

Its in the middle.

Widest champion pool and easiest lane to have an impact.

I think it's because it's the lane with the most impact. You're between two crucial objectives which are Baron Nashor and the Dragons. As well, it's probably the lane with quickest win/loss result via means of Dueling.

This is just my opinion, but a lot of games just seem to revolve around who has the better mid laner who should have a lot of map control, map presence, awareness and the ability to know when a fight is a win or loss. It's probably not quite as stressful as the Jungler who has to try to keep lanes winning, though again I think Mid Lane just has the fastest results for turning a game.

Not sure, I guess a lot of people like assassins but aren't they usually top lane? I don't really see a lot of mages around..

solo lane, best lane for a solo Q to carry with.

lol ironic i hate playing mid , i dont like mages or assassins, maybe that is why i am a support main or play tanky cc champs like