I'm not the world's biggest fan of the show, but I have seen a few episodes - and A Berry Bear Christmas is one of my favorite things they've ever done, possibly due to nostalgia factor. Bear and the gang are some of the best characters in children's television history, and I support the notion that they should come back.
I wouldn't go so far as to say that. Shows get cancelled all the time, usually for a very real reason. This time it seems that after Lynne Thigpen, who voiced Luna, died, the crew didn't really have the heart to continue. Be glad that it lasted for five seasons - one of my personal biggest gripes is the cancellation of TUGS, which lasted for only one season - thirteen episodes. Bear fans have it lucky.