Don't think it's a population problem, we had this before NB ban, but now it's more widespread and extreme.
A lot of the recent changes has for better or worse moved incentives from simply participating to winning, meaning if you don't have a good chance of winning, you are incentivized to switch to winning side.
Could this be fixed without devs/changes by the players agreeing to balance factions for good fights over gaurenteed better rewards, like they done before? Sure, but personally think it's better to keep adjusting (as long as it's not a resource drain) until you have system that does that by itself.