The people here who are claiming that shouting a single role regardless of draft order is entitlement to play that role are only arguing that the fastest typist gets to decide what they play. When you do that and offer nothing else to the table, you aren't being a team player. The pick order IS random in non ranked games so that everyone can get a chance to be the first to do what they want to do, simple as that. The summoner's code and law supports that mentality, meta has nothing to do with it.
I have my preferences of role to fill based on my skill at it from one to the next. Top being my best, ADC being my worst, in terms of popular meta. If I'm last pick and ADC is all that is left and my team didn't care that it was my worse, then oh well that's what I'm going to do.
What really should be implemented, is a PUG style matching system, where people list what role THEY want to play, and get matched with people who arn't going to fight with them over it. Until that happens though, draft order is priority, if you don't like that, play with friends, or play blind, but don't come into non ranked draft and cry for one role and refuse to do anything else, you're not helpful, you're not communicating, you're just being a pain in the ass who everyone else shouldn't be forced to appease.
Also, you all agreed to the summoners code when you posted on these forums, no where in it does it encourage or imply shouting out a single role is being a team player.