To be honest, I don't really care, if I loose planets. I only need them to buy buddyslots and I accidentally bought 100 slots last time, as the price of one Slot on the Playerpage was displayed as 1planet, instead of 150planets.
However, for me the planets have no real purpose, except that, so I don't really mind if I loose them.
And having to pay 5 or 10 planets for a car, that is used in a mediatracker of a track is not really an issue, as this case occurs maybe twice a month.
I hope with the release of some Custom Titles I'll need to spend some more planets!
