Short answer: I'm lazy.
Myself and a colleague have experimented with SCORM in BB, moodle, angel and have found it more trouble than its worth. I dare say I'll come back to it when its more robust but in the short term my team and I are happy to lose the tracking data for ease of publishing.
We also like the ability to be able to change things just before students get to them, if you've put everything in a SCORM package you've lost that ability (haven't you? not completely sure on this)
Rich