Why is the queen trade not good for black?

How did you reach the conclusion that you holding up until the queen trade? You are not asking the right question, by move 14 Black should be wondering how he managed to get a worse position after such insipid opening play from White. 3...Bf5, 4...Bb4, c5 at some point. You were playing without a plan right?

By the way 12. Bxh6 gxh6 13. Qxh6+ Kg7 14. g4 opening lines towards you king was sound. 19...f4 drops a pawn.  23. Ba4 drops a pawn. 36. Rdf2 keeps your king where it does not want to be, the pawn cannot be defended at any rate. 40. e6 wins the bishop. So does 42. e6. 51. Re6+

This is not comprehensive but it is a better place to start then wondering about the queen trade.

It's also better to ignore people that don't address the question. I am asking about the queen trade. You are blocked. I don't have time to argue and justify my question. If you want to talk about the queen trade I welcome that because I am asking about that. I am not asking people to give me a sideline lesson.

This is why I can't post full games, because people look at other parts of them and don't answer the question. So, here is the position folks. Why is a queen trade not good in this position? Black to move.

Well, we know black has poorly placed pieces in the diagram.  Both knights on the back rank, the bishop is "bad" and doing nothing.  Qf7 doesn't really fix any of that, it just gives white yet another move in a position where white already has the much better pieces.  So what is the goal of the move?  Yes, trading queens can help blunt an attack, but white doesn't really have an attack here, not even if the knight tries to come in (hint, after nc7, white playing ng3 will lead to the queen getting trapped).  So why not start fixing things, with nc6 or nc7?

Stockfish may have some more sophisticated "reasoning" but from a human perspective, fix the actual problem.  Trading queens just gives white another move to play with.  Its common sense that its not great to do that with both knights on the back rank unless the white queen is actually doing something useful.  And it isn't.  It might *look* like its an attacky kind of role, but what is the attack?  Maybe you thought you could bring the knight in, but as noted above, that isn't easy to do because of be8.  Say black plays nc6, how does white attack?  Its not there.  

Thanks ArtNJ, I was waiting to see what white would do before I committed to Nc6 or Nd7. If you go the Nc6 route it places black in more of a defensive posture I think. If you played something like a6 Bb5 and traded bishops, you would double pawns on the b file but you would also have an open a file to get some offense. Another idea would be trade queens, move the other knight to c7 and then you don't have to double pawns after Bb5.