The Real Reason I Dislike The Role Selection System
I was a huge hater of the old Ranked system (where you had to beg your team to have your role in chat). When Dynamic queue was released I was really excited because I realized that I no longer had to play Support every game (yay). The thing is however, when I was unable to get another role (I'm not terrible at any of them) I was always willing to be that person who would pick up the slack and play support. With the introduction of Dynamic queue there no longer was that "in between" or variety of roles. The is perhaps the biggest thing I hate about Dynamic queue.
In my experience with Dynamic queue, when you queue solo at low ELO's (Bronze - Gold), essentially any time you pick Fill or Support as your Primary or even Secondary.. you get Support literally about 99% of the time. The reason behind this is simple, secondary role selection isn't weighted correctly. Right now the way the system decides what role you are put in appears to be based on Supply & Demand. The problem with that is there are less Support players than other roles which means Support has the highest weight even if you choose it as your Secondary role. Picking Support (or Fill) as your Secondary almost 99% guarantees that you are going to be forced to Support which in turn creates EVEN LESS players picking Support (and Fill) because players will quickly understand that having Support ANYWHERE in your selection automatically makes you the Support (and will in turn pick something else instead).
The way to fix this is to change it so that Primary role has a high weight in the system and Secondary has lower deciding factor in what role you get. When you indicate "Primary" role you are saying you WANT that role above the other(s). The system needs to acknowledge this a bit better than what it currently does. I also believe the Fill roles needs to give a FIXED CHANCE (20%) of role selection instead of basing what role you get upon Supply and Demand. Of the predetermined choices I really think if a player is willing to Fill that it should have a HIGHER PRIORITY than players who have pre-selected their roles. When a queue is being analyzed I think the system should decide the Filled players role FIRST and then check how it could fit the other players into the queue. Logically this might seem backwards (because the player said they'd play anything), however the system can always find another candidate for whatever role is needed and this would also make for a MUCH more enjoyable experience.
As someone who actually would prefer Filling, the way the system decides things now is simply not a good method of "Fill".
I hope the system can be re-evaluated in the future to make for a more enjoyable role selection.