Its something like popular saying now, "gameplay trumps realism". Indeed you wont play a game which is boring, no matter how realistic it is. A game should be fun to play. But immersion (being a consequence of realism) adds to fun or magnifies it. So mechanics which increase immersion can be beneficial for the game even if they harm gameplay somewhat. The best is to use mechaincs which are realistic and fun at the same time. Its only hard to find such mechanics and make them work together.