From what I gather it's to speed up the process of getting from matching qcue to actually starting a match. I will admit it is aggravating especially with kindred coming out soon .
Riot has given other options for people who have experienced this quite a bit , such as people kept locking in a role even though it has been cold so we have TeamBuilder . Draft follows a generally understood pick order system .
Not having to login with not necessarily get rid of the problems that you're describing for instance someone just picks (insert champion here ) and puts a smile on them even though you call jungle first he's just going to stay on that champion and you're still be more likely to dodge the Q.