Well to be fair some people are fine with playing every role except 1 particular role(usually Jungle for me). Rather than having a dodger in my game, or the typical "can I mid?", I'd rather wait 20-60 more seconds and get everybody to be content with their role.
Heck, I'd be fine with a "I don't care how long it takes, I ONLY want to play this role" option, just so I get enjoyable games when I do play.
People say it'd make queue times longer, but it'd reduce a ton of negatives to improve the quality of games and champion select.
Ideally I would want a priority bar for each role: None, Low, Medium, High, Max. And you just adjust it for each role, so I could put Mid and Sup as Max Priority(or Sup as high if I am really feeling Mid, and vice versa), ADC + Top as Medium, and then Jungle as None. Even with autofill enabled that would at least show which players are more suited for specific roles, as the "low priority" is more suited then a "no priority", and would then be selected(You would know you're the best jungler on your team, no basis for trash talking :P). I can't imagine 9/10 or 10/10 people all boycotting 1 role, but I'd rather wait then have them forced to play it and get a cruddy teammate.