Why isn't Ranked MMR and Normal MMR the same?

Dear Riot,

Why is it that ranked and normal game MMR are not the same. I've managed my way to climb up the ladder a little bit but how am i supposed to get any better if I'm playing lower ELO players in Normals.

I honestly feel like it's harder to win normal games anyways because you get troll picks like AP shaco mid lane. I'm cool with having some fun but I do still enjoy winning more than losing.

I guess my point is that I dont want to queue with bronze and low silvers when I've made my way to gold. I'd like to continue to get better and not have to try so hard to carry every single normal game to raise my MMR there too. Ranked can be stressful enough.

Couldn't you at least make it so that in normals you play people at a higher MMR than in ranked a % of the time? Then at least players have a chance to get better or learn things from higher ELO players?