Hi!
Yes, there should always be a response to all bugs. Without a response the impression in the reporting wiki-community would be "nobody cares about our bug reports".
Would a canned "thank you for your feedback, please stay on the line, your call is very important to us" response make anybody feel better?
The reality of a project with huge userbase and limited resources is that there are more bugs that can be addressed seriously and substantially, not with a canned response that does not solve the issue, than there's developer resource. It doesn't mean "nobody cares about the bug reports" - it means some bug reports will be cared for first and some later (and possibly some, unfortunately, never). This set of priorities can be influenced by alerting developer's attention about specific bugs needing addressing, and by existing prioritisation processes, which very much include community input, but the harsh reality of having a lot of bugs dictates that giving serious non-canned attention leading to satisfactory outcome to 100% of them is IMHO not realistic.
We could of course institute the policy of "every bug should have a comment from a developer within X time" - but unless X is very large, I think it will be unsatisfactory, since getting "yes, it's a very important bug, thanks for submitting it" comment without the bug being fixed is IMHO no better than getting no comment at all.