The idea behind blind pick was to just pick whoever you want and play him/her the way you want. But as most of LoL's community seems like kind of dumb if it's about creativity, they forced a very strict "meta"-setup and they try to strictly follow it even in blind picks. Btw afaik Riot seriously fought against that meta through a long time when they finally gave up... especially that no other MOBA has this, not even DoTA. Double times funny that as the skill level rises you will see it less and less strict, with many roaming and lane-swapping and such... e.g. just watch a pro match.
In its current state it's more than terrible, I agree. I don't even play it, max with premades.
Anyway, the problems why you won't be perfectly satisfied with draft pick:
- 2-3 of your 6 champs will get banned if they are popular picks. From the rest only 1 suits the role where you ended up due to autofill. The enemy simply counterpicks your champ - and you are in a bad spot even before the match starts... You really have to have a bit more champs to draft comfortably.
- You won't get rid of trollpicks in draft pick either. I regulary see dodges, arguements and trolling over roles. And as a supp main I regulary see funny trollpicks on the opposite side - e.g. just in the last couple of days I've seen a Yasuo and Twitch support (both outfarming their adc and failing miserably at midgame) and a Rumble support (though he tried to do his best, so prob. it was only an experiment, not trolling).