You are SO right Slapshot,
BUT
Apparently many care for rank, many players seek out the things that will improve their rank, planewise and gamewise. Today the "best" planes are used by many that play for rank, with this unintrusive system they would choose other planes to pad their score.
I bet we would get SOME to look for other rides than the abundant "best" planes, that is all I see this idea will accomplish. We would hopefully get an arena with a little more diversity.
We're not upset over what people fly, some of us just feel it would be more fun with more planemodels in the MA. Is that so bad to wish for?
Check out the stats of those that score high on rank, it is safe to say there is a trend toward usage of the "best" planes.
The target demographic will not be those with crap rank/skill (not implying those are tightly related), but those that would do good in "lesser" planes but stay in the "best" to maximise score.
The current perk, score and killmessage systems already motivate people choose certain planes, this is not a new concept. This idea would hopefully distribute the motivation more evenly over the planeset.
If you don't care for score, if you don't care for perks or if you don't mind the overabundance of certain planes, I don't expect you to see any worth in this system.
At least I'm not suggesting taking choice away from players, this little thing is completely harmless.