I think the best way to fix the timidity problem is to quite simply remove the timidity at the source. That is, make the players good enough that they don't feel the need to fly timidly (and that's really not hard at all). The way to do this is to more efficiently funnel the players towards the training resources. Trainers, improvised training by players, sparring in the DA, etc etc. If somehow the AI could be used to give players an endless practice buddy that'd mold its skill level to the player, and set it up so players could "Warp" to any lesson they wanted (formation flying, defensive barrel rolls, long distance gunnery, anti-bomber fighter ACM, etc), it'd be a lot more efficient.
That's not to say that this idea's (changing the kill messages) inherently bad, either. I personally would have it so you only found out who you killed after the flight. Unconfirmed messages before then. I think all things considered the victories message on landing are best kept. That's an incentive to succeed, to compete. If some players get into all sort of dweeby contortions to land kill streaks by flying without actually fighting and earning them, that's another thing. That abuse doesn't warrant forbidding proper use of the kill messages.