I get it, there's no reason I can ever justifiably expect a developer to fix my pet bug, given that they choose what they work on -- except that if they fix the bug, the software will be better, which should really be the goal. My bug-reports are objective, carefully researched, and properly written, with minimal test cases / repro instructions, required logs, etc. etc. -- and I'm a developer myself, so I understand what's needed.
No, I don't have time to figure out how to build, test and isolate bugs in every product I find a bug in -- the developers can do that much faster than me, they are already set up to build and run the code, and they know the code better than I could hope to. So reporting bugs is my contribution. I would love to see a bit more responsiveness to contributions across all open source projects, even if fixing bugs feels like laborious busy-work.