People go for the kills in order to maximise the gold and faction point payout with the dailies, courtesy of the new, crap, Treasure Galore, 2nd of July update. This is yet another of the faults of this patch. So a high score, ultimately means closer to the gold and faction points given out and you can only (really) do that with lots of kills and of course a fast mission time and low team death count. Essentially, it's the first 4 matches of the day that are paying out, after the Treasure pot, which there's no guarantee of winning (I just lost my one for today earlier along with it about 10k gold and 4k faction points).
I wouldn't call it a rant, but a genuine concern of of what happens when you lump all the real awards into the first three or so games of the day.