I must admit i'd be pretty annoyed if one of my ships were to be stolen whilst out in the SRV, but then again, I leave a very small window of it being unmanned on the surface. That's not to say it couldn't happen!
I think it would be a brilliant game mechanic, if the risk/reward system was balanced correctly.
Want to steal the ship? Cool, have a go. Surely some method of hacking/code breaking must be present to allow a timer to begin and thus notify the ships owner whilst the thief attempts to power the ship up and leave.
If successful and they manage to escape, the bounty needs to be pretty hefty for such a heinous crime, and a flag put on the subscan information saying "stolen."
Big rewards for turning vigilante security I think!
And on the other side of the coin, it open a whole new world up for GTA style respray shops within shady asteroid neighbourhoods to loose your stolen status! haha!
BTW, I am no griefer and I have not once attacked another CMDR, I just love how deep the game is, why not go further?