Why isnt there a way to trade in your old starships for higher tier or for some sort of credit (dilithium? lobi?).

I have six ships that I never use anymore because they are tier 4 and under. All I can do is dump and lose them.

It would be nice if I could sell them for lobi (50 per ship?) or dilithium ...or trade 2 ships for 1 token of my current rank.