If they indeed don't have anything to do with the content or development like they've claimed, then it's simply a distribution platform that provides/hosts games. Sure you're welcome to bitch and whine at them all you want. A more apt analogy would be like blaming Sony/Playstation or Valve/Steam because you don't like what some third-party game devs are doing on a game provided on their platform. Sure, both Nutaku and Steam take a cut out of the customers' money as the games use that platform/distribution service, but in the end they're not the ones that develop/update those games. So feel free to bitch away at the customer-facing entities 'till you're blue in the face; unfortunately it won't fundamentally change anything about that game's development or update cycles, until the actual game devs do something. And yes, both platforms do indeed offer customer support, where you're free to go to try and demand those refunds as that's your prerogative.
While you seem to really be reaching with that analogy about brick and mortar stores, since we're discussing game-distribution platforms and game development, it'd be more akin to blaming Sony because a game by third-party devs that you got from their online Playstation store doesn't meet your developmental standards. Not only that, but it'd be after you downloaded that game for free, which has micro-transactions that you chose to buy, spent countless hours playing, and then trying to demand a refund for those micro-transactions in that free game. Let me know how Steam/Sony treats you with that, and best of luck to you there bud!!
Things like botched development schedules or bad updates are on the game devs. While we can moan about Nutaku all we want, they don't actually handle any of the content pushed out in the game. It's really not a hard concept to understand. Also can you source your claim that DMM is the parent company of Nutaku or vice-versa? Afaik, Nutaku simply partnered as their distributor. Because your opening claim of "if you're owned by a parent company" is confusing to me (or maybe just trying to be plain misleading?)