Ranked (Team Builder)

Can someone explain to me why team builder isn't an option for Ranked? Other then possible longer Que times? Majority of the fights start at Champion select because someone didn't get their role, why? Because of pick order.

Now I am a firm believer that if you play ranked you should be able to play all roles in case you get stuck with one you normally don't play "Keyword being Stuck". Why should anyone avoid being stuck in a role they don't feel like playing? It is common knowledge that a person will more then likely play their best or better in a role/champ they are in the mood to play.

If I Que up and am feeling Top or Mid and I get stuck with support I'm not going to do as good because I wasn't in the mood to play support. I Think I can claim by going to top/mid all the time and I get stuck with jungle/support all the time then what's the point?

I've played a lot of games, but League seems to be the only game I know that forces you to play a role you don't want to play for 20- 45+ minutes in ranked. Maybe in higher elo you can say hey I wanna play this role and they will give it to you but in low elo it's basically fuck you , you fill or something along the lines of or end even end up playing a champ like ashe jungle because they are in the mood to play ashe but get's stuck with the jungle role.