The stupid thing about kill points is that the best way to farm them is not use them. But having a mechaninc that reward palyers for killing ads is more than welcome for me, it should be the first concern anyway. This system with many other rewards certain character over others, and for that reason I think this game assist should reward kill points. I wouldn't however necessarly reward damage to boss like entity because you would risk to have the opposite problem. Immagine having three snipers and long range in your team focusing the boss while being swarm by ads, and someone has to try to keep them alive. A change I would do is to give 20 points for engineers and looters, it isn't hard to kill them, but it is good reinforcement.
The score system is a bit shallow hovere. The best way to get a good score is to get a good team score, and do the mission fast with few death as possible. Also some parameter are a bit stupid, raiders extracted is quite arbitrary. But the biggest offender is the survival score, getting trought a survival isn't a feat unless you play a native, and in orther to get a good survival score you need a bad resistance score.
To get an high score at the end of the month you need to have an high mmr, and to get high team scores over personal score. To get kill points you need high spawns rates, and so you need an high mmr. There is no way around it and the game should tell you.