Well, if Riot wants Q times to become more acceptable perhaps they should actually incentivize solo players to play the game since pairing will be slower if there isn't a large base of solo players to fill out premades.
As a primarily solo player I've played like two-three "ranked" DQ games over the last 10 or so days and despite having success in those games I don't really find myself increasing my play rate because I simply don't feel like playing at a higher rate.
From what I've heard, this quarter is the first time in history Riot has lost more players than they've gained, if it's true, it might explain why Q times are becoming longer, me personally, I haven't noticed any difference, but considering I haven't been playing much other than bot games I wouldn't really know anyway.
For whatever reason, some players simply seem to be unhappy with the state of the DQ and thus, play other modes or simply do other things with their time.