My reason for not wanting to lose this feature is purely personal. My SL partner lives nowhere near me in RL. Our easiest way of interacting is through SL. We both enjoy it very much. With the avatar online hud that I have and that he has, we are less likely to miss the fact that the other has come online. This insures that we have the maximum amount of time together.
As for the third party viewers, let me just say this. I find the Linden viewer so user UNfriendly that if it were the only viewer I was able to use, I would probably have never stayed in SL.