I think it's because that license (and the one the Giants still hold) are being taken by "quick fix" teams.
The Giants was assembled together rather quickluy after the demise of the Titans (who were put together after th demise of the previous Giants team...that whole license has a bad history traced right back to the old St Kilda SPectre days)
The Cannons one saw the Cannons Mark II fold very quickly under the rule of Cal Bruton, once again because it was a quick fix when Cannons Mark I went into receivership.
The NBL needs to stop the quick fix solutions (as viable as they may seem at the time), and allow a club to put together a sound financial base.
Thats why I think the Tasmanian and Gold Coast teams (or perhaps Geelong??) should be given the chance before we see the license go back to Newcastle or a Melbourne metro team.