Honestly I feel like half the player engagement dropoff comes from the fact that once the initial wipe happens, that's it. That's all the new stuff you get for the next 6 months. Don't get me wrong, .14 definitely looks pretty meaty, even if it's missing a few things announced on the roadmaps for this year. But I miss the first couple of .12 wipes where it would be something new to keep you engaged every month, month and a half, whether it was something as big as a map expansion, or even just a couple of guns and new chest rigs.
Considering how much quicker it is for people to get to level 42 thanks to general player knowledge and skill improving over time, it feels like people burn themselves out very quickly, and that's inevitable when it comes to a game like this, but just a trickle of new shit to use would keep people engaged for a bit longer, I reckon. I also think with more eyes on the game thanks to Arena probably bringing a lot of new people in, it might not be a bad idea to make development look more lively.