Although this is an interesting suggestion, I don't see the value of these coins when there is pretty much nothing to spend them on.
If you're worried about "getting people to play" through means of a competitive system such as the one you've suggested, our upcoming update which will feature permanent stat saving (kills, deaths, wins) and website leader boards in different categories, will be more appropriate.
Personally I'm not quite sure what the majority of you mean by "getting people to play", since I've been online on several occasions in which there are a good 10-20 people playing at a time -- though granted, not all of them care to speak English, but that doesn't necessarily invalidate them. As with all games, the *peaks* --if you will-- usually come around the first week of a new update, as well as the beginnings of weekends (Fri-Sat) -- so if you're worried about finding someone to fight, those would be the more appropriate events to wait for.
I get that it's a hassle to bring it up, but it's also plausible that quite a few members are simply waiting for full on character customization -- I suppose not everyone's down with the jackets (though they are pretty cool, admittedly). Once that update (or another Jutsu update -- who doesn't love a new way to kill someone?) comes along, it's likely you'll see at least a temporary increase in PvP activity.
About the Afk-killers...why would you stay still in an open area? If you intend to be afk, why would you even bother staying in the warzone at all? Hide in one of the further-reaching corners of the map, or simply switch out to the login-screen; PvP is open to all on the current map, so it seems a bit foolish to ask people to *avoid you* while you get your crackers. If ever there was a time to *start* learning "How-2-Shinobi" guys, now would be the time.
)(^_^)(~~No Offense Intended Stamp~~)(^_^)(
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