Because it's not always the case of just one minor patch. You have to figure that a lot of these games have fairly complicated backend architectures. You could be talking multiple different services, all with different configuration requirements.
There's a big difference between designing a server so the public can running it, and designing a server for internal use only.
If they can't fix their own software to work without their own servers then they are lazy at best and incompetent at worst. There are no valid excuses in claiming a fix is too difficult when you're the one who designed the problem to begin with.
There's a big difference between designing a server so the public can running it, and designing a server for internal use only.