Hollywood's in a recession just like everyone else. Studios are slashing their output, and networks are running Jay Leno and reality shows instead of scripted dramas, which cost more because they employ many more salaries and resources.
Hopefully O'Reilly is an acting teacher or something, because his IMDb listing since DS9 ended is very, very thin. Not much in "other works" either except a couple of audio book voiceovers. Hertzler's post-DS9 era is better, but it includes a lot of VG voiceover work, which doesn't pay as well.
You can bet your behind they are doing it for the money.