ATRAC was a superb compression format in my opinion. By far the best I ever heard.
I would go as far to say that Atrac at 132kbps (I believe that was LP) was superior to 320kbps MP3 on my NWZ-E455.
It is a huge loss to me. Think of these geeks in the lab slaving away at improving it for years and then seeing it die forever. I think it should be made public, open-source. Sony have nothing to lose by doing that.
I just don't like the MP3 players as much as minidisc either. Just recently an album disappeared from my player without warning. And I have a perfectly good minidisc player from 2002 but no software to support it. I suppose the old style players with the replacable batteries lasted too long. Now we will have to buy a new MP3 player every 2 years or so and in this way benefit the economy.