I collect them to pull the battery out of.
I've got a bunch of rc pieces I'll probably never need due to simply not needing all 20 cables or whatever in the pack. So all my leftover jst connectors go to "old" lithium batteries, and I use them as little power banks for my phone, and arduino stuff.
They typically don't last too long, and range between 200-1000mah, but it's something that isn't "taking up space in a landfill or being crushed and setting something on fire"
The Maquis have a lot of good points.