I've decided that LL is expecting a big influx from Steam and wanted the bug-reporting system cut back before that happens so that expectations will not be raised from usual MMO bug-reporting methods and things will be easier for them.
For current SL customers the situation is summed up by this comment from Latif Khalifa:

Latif Khalifa
on September 7, 2012 at 01:50
Another thing that is important to remember: I found workarounds for literally dozens of problems by searching Jira and reading comments where someone would point out a way to do something without crashing, or something similar. All that valuable knowledge sharing is killed with this.