I see your point; I can see why some people would like to see a change - however, if there were anyway to get a ship off the market, believe me, there are enough creative gamers out there who will find a way to "cheat" or take advantage of the situation where the system is abused to the point beyond what was intended.
I personally like the system as is - once a ship is on the market, it is stuck there until sold. It is simple, straight foward and it affects all styles of play the same. I would like to see the ability to perhaps upgrade it in an effort to improve its value and get it sold, ie, howkers, sloops, etc. as sometimes it's hard to justify even a price of 1 credit for these vessels.