Dunno about na, but on euw server the lack of support is really out of hand.
What happened is simple :
Slightly less support than other role in dynamic queue
So when you put support as secondary, you are slightly more likely to get your secondary.
People notice this, start putting anything else than support as secondary, just to get their main post.
This make the problem worse. Ther's even less support, now you ALWAYS get support if you pick it as secondary.
Even people who were OK playing support more than half the time stop selecting it as secondary, because now it's 100% of the time.
Only main support are left.
also, select any other roles, and your game should take 1/2 min to start. Select support as secondary, game start in less than 5 sec.
Solution ? Garantee at least a certain percentage of your games on main role. Like : you've played your secondary role the last 2 games ? For this one we increase the time for the game to start until we find a tea with your main role free.
Hope that if people know they can put support as secondary without playing it 100% of the time, people will start to play it again.