It's better to have loved and lost than to have never loved....
I think it would be quite a cool feature. You could cross reference how much you were paying for the output you got on court and as not everyone uses the fancy wage calculators, for someone buying off the transfer list to have a bit more background to the players training/previous wages may be of help. I can't see a downside to having it unless the data isn't remembered or is difficult to display.