An indicator to the actual stance when on first person mode is becoming necessary, it is hard to know the stance you are in with no UI feedback. I can imagine there will be plenty of 1st person only servers, where this will be sorely needed.

In real life the body gives you plenty of feedback to know whether you are standing up, sitting down, or semiprone and breaking your back muscles. This is not reproductible on a videogame, making a hud indicator a necessity.