See, i'd agree with you except you can buy Orc Massage on Steam, once, and have access to every update for the rest of the dev cycle. It's not like they're re-charging you each and every month for the game.
I bought it last year and and have gotten every dev-update and game update since then, total cost: 12$ or something.
If I wanted to get every Eromancer update for Pure Onyx in the past year? $5 a month for a year at least.
For sure there are devs who milk the process, Orc Massage ain't it chief.