The developer is making three games simultaneously and is still managing to bring out content for two of these games every 2 months with reasonable amounts of content. I think there's very little to complain about in regards to siren's work-ethic. Most of the hold-up for both Zombie's Retreat and Town of Passion seem to be in the art department, and that's mainly because the games are not the artists' main focus. (and ScarlettAnn seems notoriously reclusive.)
Compared to some other games on here, I would hardly describe this as milking anything.