To be fair, SGC just recently came out, and I enjoy playing it quite a bit. Not sure if they've fixed the SG2 chests or not, but i'll probably start playing it a bit more when they do.
As for deleted maps/maps that aren't on the servers anymore, they were deleted for a reason, and could be added back if enough people in the community wanted it.
And maps that simply aren't played as much, it's just what the community wants to play, and majority wins. I enjoy many maps that are rarely played, and it's saddening to know that they're dying out, but it's all a part of being here. Going through change.