While Trello is simpler and snappier (not snappy, but snappier) than anything Atlassian has to offer, it is quite limiting as well for task organization.
One problem is, that not everyone is willing to educate themselves and people expect to be able to use things immediately. This causes the push to dumb down things into a limiting experience. If I were surrounded by only technical people, then a plaintext file like an org-mode file with predefined todo-labels, commited to a git repo would beat all of the Jiras, Trellos or whatever out there and it would cost not a cent and be safer to work with, as everything is stored in git.
