What about hidden services? In my opinion that's the real heart of Tor. I think the value of exit nodes will start to wane as Tor gains a larger and larger user base and becomes it's own truly viable darknet. As it stands the majority of security related discussions I've come across regarding Tor strongly discourage spending any large amount of time on clearnet services anyway as this create many potential security/privacy risks.

"With that in mind, what user would want to operate an exit node?"

All of the people who have already been running exit nodes for years? Those who don't mind getting that terrible knock on the door? Those who have already had that knock on their door, sometimes more than once, but who live in locations where they don't need to fear their local police?

     what user would want to operate an exit node?

I'm thinking that malicious individuals would run Tor exit nodes in order to sniff traffic.

In theory you could run an exit node with a locked down exit policy, e.g. limited to web traffic which is routed through an IWF compliant proxy, disallow HTTPS and/or payment processing sites, add an HTTP header for reporting abuse/requesting blocks, etc.