Getting Solo-Que back comes at a price
I have a theory as to why normal draft is being removed, and it's because solo que is coming back, basically, riot still wants their Dynamic Que -"Flex que" and they are worried that there are going to be too many players spread across the 3 different match types, causing que times to be longer in all of them.
SO if you were to theoretically remove one of these ques, it would corral many of the players from normal draft into ranked, causing more people to be in ranked ques, thus having **shorter match making times ** I would like to credit this to Riot having this idea that they must "Force" dynamic que (flex que) when quite a large number of players just don't want it.
Hell, even in past posts from them when they "decided" they weren't bringing solo que back, they said that this was the very reason, that que times would be longer because of the spread out players.