Moderation of any site that lets users contribute content, regardless of whether it's on the Stack Exchange network or not, is important as it directly leads to a higher quality site. A higher quality site is much more inviting to new contributors and readers, which means the site will grow in both content and activity. In the case of Stack Exchange, this is precisely why users can gain access to moderation privileges: Giving folks who are familiar with the site the ability to help curate the content that's on it directly leads to a cleaner site. Stack Exchange's A Theory of Moderation touches on this beautifully:
We designed the Stack Exchange network engine to be mostly self-regulating, in that we amortize the overall moderation cost of the system across thousands of teeny-tiny slices of effort contributed by regular, everyday users.
To be clear: The review queues are completely optional on Stack Exchange sites. Just because you can access them doesn't mean you have to - But they do serve a distinct purpose of bringing content that may require moderation to the attention of the community members who can help deal with that content.
But... This doesn't really motivate users to actually help out. "Why should I even bother?" is an absolutely fair question to ask. I know that you said your question isn't necessarily meant to act as a response to the user who you mentioned, but I feel that the question of "Why is moderation important?" can be answered rather neatly if we break down what the user said point-by-point.
I mean, when I look at "Top Questions" page, when I find a question I may care about, I'm doing the same thing as during review queries: upvote/downvote, comment, suggest edits, answer, flag, ignore, etc.
First off, good! Voting, editing, and flagging are all very important, and are great to see from a user who frequents the top questions. Though, not all questions/answers that you would typically find in the review queues are going to end up in the "Top Questions" list. Those questions/answers need to be addressed too!
So essentially, review query sounds like a way to attract my attention to questions/answers I don't care about
Well... Here's a more important point: The review queues call attention to questions/answers that the system feels need a second look by experienced users. As to whether you care about that content or not: Users can also filter their review queues by tags so that the content they're reviewing is at least mildly interesting to them. Subject matter expertise is not typically required when in the review queue, but it certainly helps!
The ability to filter your review queue experience to the tags that you feel are relevant to you harkens back to something "A Theory of Moderation" covers; each small action by individual users in an effort to help moderate Stack Exchange sites adds up. You can choose to only help out with your corner of the site, or the broader site as a whole. Each action you take that helps keep the site a little bit cleaner adds up to the whole site being that much neater.
and, well, I don't care what happens with them. Moreover, it seems that the chance of encountering crap in review queries is much higher, and I believe that the crap I see already is more than enough.
Ekadh Singh touched on this in his answer, but broken windows theory is pretty relevant here. If your well-written, higher-quality contributions are lost amid a sea of content that's extremely low-quality, spam, or otherwise bad... For what reason should other users, or even guests, wade through the sea of dirt to find the gem that is the content you wrote? Worse, what's stopping other users from seeing these low-quality contributions and thinking that they can contribute similar-quality content?
Raising the overall quality of the site by removing the awful-quality content helps make the site look much better, which in turn makes the contributions you've made that stick around, and are upvoted, look that much better. Have a bit of pride in the place that you've contributed to and help make it a little bit cleaner from time to time. The site, and your peers on the site, will appreciate you for helping out!
