Hi first post on here! As mentioned above it looks just like a case of balancing the value inputs and outputs in the game. It's probabaly something that'll only be fully resolved once the caravan arc is finished and the dwarven economy is fixed.
At the moment prepared meals, clothing and goblinite are all huge money faucets that don't have anything to provide a sink (They also don't require many dwarf jobs, which is doubly bad for the dwarf economy, but I digress).
The goblin item issue could be addressed partly through changing traders so they have more developed preferences (for example not buying undecorated goblin sourced items and undervaluing them even if have been decorated*), and removing GCS item drops from the grunts. Some sort of inflation for trader prices would be a good thing to have also, if the number of items the traders bring is static.
If you were going to make goblin items unsellable, or low value even when decorated, you'd be best to allow clothes to be recycled- allow them to be 'melted' at a loom back into thread at a % chance of recovery. Otherwise you're forcing people to atom smash 'em to save their frame rate. Making wear on items repairable with thread, and allowing eventual item destruction through wear & tear, would tie into this nicely. Jobs for all those non-legendary clothiers/weavers. Of course, now you're starting on modyfiying how clothing works, and that goblinite rebalance has created another few months of work...
*Why a dwarf would want a soiled goblin loincloth that doesn't fit him/her I'm not quite sure, even if there was a masterful image of dwarfs slapped on it.