Because she needs the work?

Gillian Anderson Wants X-Files Sequel
Gillian Anderson is interested in reprising her role as FBI agent Dana Scully from the long running TV show The X-Files.
According to the 37-year-old actress is keen on picking up her FBI badge again, now that she’s had enough time away from the character she played for nine seasons.
While plans are still simmering for a sequel to 1998’s big-screen X-Files movie, it apparently won’t be green-lit until ownership rights are cleared up.
“It’s become a bit messy,” says Anderson. “I think the intention is that we will and we hope to – and that, hopefully, by the time we actually do, whenever that is, people will still give a damn.”