IMO, it should be an arena setting. That way, during scenarios and events, if you happen to crash in a death dive (on fire, missing a wing, etc etc) you can do some damage as a last ditch thing.
Most events and scenarios are 1 life per frame/time anyway, so if some one do decide to crash a perfectly good plane, it's against them and their team.
+1 to the wish, but for scenarios and events only. Make it equal to a 1000kg bomb for all planes (keeping it simple) and it should be fine.