Honestly, the system would work far better if more people were willing to take support as their secondary. While it was rather spotty when they introduced the system, many of the kinks (i.e. always getting support) seem to have been worked out.
I have been enjoying the results of doing so significantly:
- If I haven't been given support, it is probably filled by a support main
- I've been getting my primary role rather often (about the same as queuing Jungle/Mid or Jungle/Top)
- I don't have to worry about bottom lane snowballing against our team since the support actually knows the role
Bonus: The system has stopped autofilling me into ADC.