I can't even begin to list the ways this would end in disaster. Every scenario where you tie some sort of compensation to a subjective metric ends with one result: the death of the site. Okay, maybe death might be a bit of hyperbole, but not by much; the site becomes a ghost town, experts are gone, and it's swept up and relegated to the dustbins of historical archives.
Here's what's going to happen as soon as this becomes a reality: Moderators will resign. Maybe not all of them, but a very good chunk of them; the primary motivation behind being a moderator right now is to help the site be better than it is. A worthwhile endeavor in it's own right. As soon as you introduce compensation into the mix, you're changing the entire motivation and obligation aspect.
At that point, no only do you have less moderators to deal with the incoming questions, you're also going to shed experts on a regular basis; burnout will claim them in stages, as they struggle to keep up with maintaining the quality and standards they're used to.
This will lead to a spiral of quality decay, going faster and faster, until inevitably, the only experts left are the moderators who believe the compensation is worth the effort. Which...won't last long, as not only are they only ones left to do all the work, but now they're going to feel they're not getting paid enough to do it.
All this, and I haven't even started on the compensation metrics. Here's exactly what will happen: whatever metric is put in place will be gamed to maximize that compensation. If you're doing a job, and you can manipulate it to make more money, you're going to do it; after all, your motivation for doing the work is to get paid. So anything you can do to get paid more will happen.
If the metrics are based on:
- users: incredibly simple to make bots to make accounts.
- question views: ditto
- number of questions: reopen and undelete everything. Nothing can be closed. War with community ensues, ghost town happens even faster.
- number of answers: bots with markov chains to make nonsense look like answers.
Not one of these increase the quality of the site. Most of them actually result in the site dying as those left standing pursue maximizing their revenue.
So. Money for moderators bad. If you expect your community to invest in making it better, paying them, by itself, is bad. Tying said compensation to measurable metrics makes it even worse.