Question: Can any chess engine tell you why a move is bad or good? For example, say a chess engine says the score against my opponent is currently +2 in my favor. I then make a move and my score drops to say 1.4. Can any engine tell me what I did wrong such that my score dropped from 2 to 1.4 (assuming I didn't hang a piece or pawn etc.) 

It seems to me that having chess programmers make their programs even stronger is now pointless and it would be much more beneficial to the average chess player if they could have their programs instruct us why a move is bad (or good), assuming they currently cannot do this.

Answer: 
Yes, I have seen programs that attempt to explain why a move is good or bad in language. Chessmaster 9000 would do this.

Many engines will show you the best line for each move. So it can tell you that if you play g6, it expects the game to go f5 gxf5 Nxf5, whereas if you play b6 it expects the game to go a5 bxa5 Bxa5. Often from there you can see why the move was good or bad. But sometimes it's still very subtle.

There is a tool [here](https://hxim.github.io/Stockfish-Evaluation-Guide/) where you can input a position and it will tell you exactly why Stockfish evaluates the position the way it does. It only works for a static position (it doesn't look ahead at all), but it's still interesting.
No.
Although Chessmaster as mentioned by everyone can tell you some basic things like if the following line will result in an exchange sacrifice or you may lose a pawn and so so.

But you can also analyse this yourself by playing down the lines. There are no chess engines nor I see any in the near future that can explain why the move is good/bad unless it will cost you material difference. As a engine may have played a move to improve his position in the future say like after 50 moves. There is no way it can explain to you why this move will result in a better position after 50 moves.

Also major chess engines in the market like Stockfish etc. do not even bother to include such features as the level chess engines play at are completely different and very hard to analyse even if we are provided with explanation of every move.