i'll quote a post i made back when new draft mode had just replaced teambuilder:
I do agree with what you say [note: i was answering a guy who was asking to keep the new normal draft AND teambuilder], but i would rather avoid having too much queues, which would make waiting times even longer. On the other hand, even if we bring back TB as it was, we can't really remove any other queue because of how different they are. In particular, TB and blind pick are different because you play the first when you want to play a certain champion in a certain role, but maybe sometimes you will want to play blind because you don't feel like choosing beforehand.
So here is my idea: we keep 2 queues, new draft mode and new blind mode.
new draft mode is the one they are testing right now, so there is nothing to add here
new blind mode will replace blind mode. New blind mode would be very similar to new draft mode, as in you can pre-select your role or fill (maybe giving you the chance to choose only 1 role, though), but it will be different because once your team is assembled it works just like blind mode, which means you don't get picks like in draft mode and there are no bans: you choose the champion you want, and you don't see the enemy team until the game starts.
This way you can either choose beforehand what you want to play or simply go in with the fill option. Because of this, we don't need to keep TB and blind mode as 2 separate queues anymore.
The only scenario where you can't actually play the champion you want is if someone else on your team select that champion before of you for the role he's been assigned to (example: you go in as supp and want to play poppy, but another guy who entered the team as top select poppy faster than you). However, that shouldn't happen that often, and is still way better than when TB didn't exist at all, since at least you are sure that you will get the role you wanted. It's a bit of a flaw compared to TB, but i think it's acceptable, because we get lower waiting time in exchange. You probably won't agree with this, though... it's a matter of personal preferences, in the end.
So basically a queue similar to TB because you can choose even only 1 role and there aren't bans, but that gives you the option to also choose more than 1 role, or even fill (which means it's more flexible than TB and allows sensibly shorter waiting time) and it post-pone your champion choice to after the team is assembled, so if you want you can choose your pick based on your team composition (because sometimes i didn't really like playing TB exactly because i didn't want to have to choose booth my role AND champion beforehand, and i don't think i was the only one).
mid. It was a necessary prospect of team builder and it prevented the full on trolls that you often see in blind pick.
in something like tb then get completely screwed when it turns out I'm laning against a 
