I would imagine there's a priority level to the bugs.
Bugs that interfere with the ability to actually use the boards are highest priority, bugs that don't interfere with the actually running of the boards are lower priority.
When the script in the pop ups to change usernames/logout, and send private messages wasn't reading right, the staff was on it right away. It interfered with our ability to use the boards, but someone receiving emails when they opted to not receive them... well, is incredibly annoying, but it doesn't prevent anyone from using the boards.
I just can't imagine how the backline on development is like. There's probably hundreds of problems that pop up before we even see them that get fixed, then quite a bit that sneak through and they have to clean up later. Then there's the people like me that bug the staff with minor stuff like merging the usernames on to one account :p
Also, there's always those people who complain that 'this isn't in yet' or 'that hasn't been done yet', I'm sure they've gotten their fair share of "Why isn't Yuku out of beta yet! Get all those features in we want!" and trying to appease everyone is bound to be difficult. I remember a few months ago when they said Yuku would be out of beta in 2007 and it wasn't how many people were complaining like mad. (The whole 'You made it seem like we had to switch over to Yuku now but it's not done!' crowd)