I'd hardly call The WarZ a case of "we could do that but better". The devs could see how popular DayZ had become so took an existing game (War Inc) where most of the mechanics were in place (including pay to play), effectively modded it as quickly as possible to match the primary features of DayZ and get it out there before the DayZ stand alone. As far as I can see, nothing has been implemented better.
I never get these "but its a rip of of X game!" arguments, sure it saw how successful Dayz was being and thought "we could do that but better" if everyone had your logic on not improving on an existing idea because it already exists we would still be driving around in ford model A's