Those of us playing since launch remembered a time when the Sell button was one of the left side cantina buttons, where you could sell gear. It was removed within six months, with the odd explanation that players were unknowingly selling gear they needed. Since then people have asked countless times fir the ability to sell or convert gear, and you can see how well that's gone over with the devs by the fact that it's still an issue.
The other way to look at "useless" gear is that it's a freebie. You'll never have to worry about that slot ever again.