HACKERS are killing this wonderful game.

I'm just a gamer dude, not affiliated with EA at all.

My experience so far has been pretty good.  Maybe I've been lucky.  I've only seen 2 people (one of them multiple times during the same day) that I was for sure was cheating (i.e. insta headshots).  I reported them using the in game method of reporting.  The overwhelming majority of the rest of the time there hasn't been people like that.  Now I'm sure there are cheaters in other game matches (I'm not naive) but not the really bad ones like the ones you describe.  Maybe I'm super lucky too.

Yes there should be a auto-ban feature for egregious cheaters like insta-kills.  Seems like FairFight should be able to do it, which this game is suppose to have.  I would bet it isn't working optimally.. in fact I remember seeing something about it but I can't remember where (on here or on twitter).  From what I recall it was "working on improvements to fairfight system" or something like that.

PvZ:GW isn't the only game that has cheaters.  It's virtually impossible to stop them unless you have proprietary hardware like Xbox1 or PS4 that hasn't been reversed... even then there can be tricks sneak in other ways (anywhere from controller mods to DNS server cheats and beyond).  Gabe Newell has some pretty decent descriptions on it.  Mitigating them is something that should be striven for.

I have faith FairFight will be improved for this game.  And whatever specific exploit is being used to get Insta-Kill... that needs to be patched if possible... otherwise FairFight needs to pick up on it quickly.