For me it's a dopamine machine. I get my doses of lacking dopamine from completing things.

Agents let me complete things in parallel all the time.

They also let me build tools that manage all the attention-grabbing things in my life. Something I've been meaning to do "tomorrow" for a good decade.

I've already built custom notification tools for all the "I'll just quickly check hn/lobste.rs/tildes/whatever" so that they'll tell me if there's something actionable, closing down the rabbit hole for me. My email is pre-filtered by an agent that pings me if there's something urgent. My IRC client is custom-built for the specific way I use it etc etc.