I think that Discovery wants to kill off this channel. But its already under contract and they do get some $$$ for it. So they are just neglecting it. I also suspect they don't want the bad publicity that they'd receive if they had done something like swapped it over to Planet Green. So I guess that they have cold feet on killing it off, so instead it just doesn't get much investment.
But hey, I haven't watched the channel in years. I used to love Wings, but after a while there was only so much footage available from WWII, Vietnam, Gulf I, and 50s/60s test footage. It ended up being that I felt I had seen everything and that the shows I was watching were being stretched to fill as much time as possible.