Look, I do agree with you in a remote way, but not totally.
Maybe for non-rated games it could be implemented, and I agree that in a "Friendly Game" that there is no reason why this should not be there.
However, I do not feel that it should be an option in a rated game. I myself have made many foolish errors while playing, and I have had to live with it. Consider this, you make the move, and only after your opponent has made his/hers do you realise the mistake. That is what chess is all about. Considering your options, checking your move before you do it, and finally making the decision to make that move.
Basically think before you move, not after you move.
Secondly, with a take back option, certain players might use this to annoy the hell out of their opponent, making a move and then retracting it over and over and over. Thus ruining what should be an enjoyable game of chess.
I do see the pro's of a feature like this, for example in non-rated games, but I also see the cons for rated games.
Have a good day, and thanks for the constructive post