Why is it disabled? Enable it! How should I know in advance that I accidentally delete something?
1) Most people don't expect it to be enabled and would be annoyed to find out, that files, they believe to be safely gone, are actually backed up somewhere (it's not like a local recycle bin, where others do not have an access too anyway, this is about remote and possibly shared system).
2) It requires a configuration of recycle bin location anyway, so it's not like that it can just be "enabled".