An option for "FIll except X" could potentially be added, but the current Fill is just saying "fill anything"; it is not saying "random". The least desired role is Support, so obviously you will get Support most of the time.
Well, if you don't own any support champs, now would be a good time to spend some IP on one or two of them...
Or you could be a jerk and plan to play an assassin or mage or tank instead of support. I actually won as bot lane Kha'Zix with a mage Heimerdinger even though he was supposed to be the support. I didn't like that he was picking a non-support but since I was playing a non-ranged champion I couldn't exactly demand that he pick a support either. Plus I could heal myself anyway so it wasn't like I absolutely needed healing. Still, it was a hard game. I used to play Rammus in bot lane as a tank(only with ADC lane partner, never with APC lane partner) but the current mastery pages as well as the buff to Ardent Censor make playing a support very good. Also, tanks are amazing in the jungle at the moment. I actually think off-meta picks are okay for the bot lane, but a support should always be in the support slot. I actually think that very popular 'support slot' champs that are not real supports IMO should not be there, such as Blitzcrank(tank) and Thresh(marksman) and Annie(mage). Don't own Thresh so I can't know which slot he ought to be in, but bot lane(let someone else be the support) might not be bad for him and Blitzcrank is fine at jungle. I haven't been playing much Annie lately, but in my previous experience she hasn't had a hard time killing minions at all so she might make a decent top lane. Putting a support at top, mid, or jungle positions is optional, but at the support slot it is just great in general. Even if your bot champ is having a great game, a support could be useful to any of the other 3 champs that might need help. It's just too good. But it is possible to win even if you don't have it. Just not very likely.
The problem is that support is not fun. It is passive and reactive. It is rarely ever active.
Couple this with the fact that you are hated by your team if you ever try to do anything as a support and you end up with a situation where nearly no one wants to play support.
