So I'm at Pilot Level 16 at the moment, all of the HC injection Pilot levels are behind me, and I have to say that being forced to win a match to gain a small HC boost each can become frustrating at times. I'm the sort that just wants to play siege, and I just want to play until I'm tiered of it, whither I win or lose. With only having a first win bonus per mode (And otherwise only bits and pieces for completing matches) I'm getting a bit discouraged.
If I want any bonus at all I have to win... which means I have to play other modes that I might not feel like playing, and play them until I get first win, then drop out of the server, play another mode, do the same thing, and by the time I've gotten first win on the thing I actually want to play, I don't feel like playing anymore. It also makes me prioritize winning over having fun, or having a good time, meaning that repeated defeats are just seen as roadblocks instead of something that just happened and to try again.
Personally, I think the first win thing might be contributing to your *Everyone leaps out of the match as soon as it ends* problem, as well as to incentivise dropping out of games that aren't going your way after a person's fifth defeat that server. It isn't the sole problem, but I as a newer player am feeling a bit of strain of having to prioritize making HC over actually doing what I want to do because that next Mech isn't going to buy itself you know.