I'm perfectly fine with imaginary worlds that don't share the same physical laws as this Real World of ours, but I do expect that at a high enough level there's some consistency to the laws of any world.
I qualify that with "at a high enough level" because I'd even be good with an imagined world in which different parts of the universe operate under different physical laws... as long as there's some plausible high-level explanation for that effect. Maybe (as in more than one fantasy novel) there was a horrific magical disaster that shattered the universe into multiple planes of existence, each with its own slightly different physical constants but all interconnected in the same universe. Or maybe -- and it's conceivable that this is the case even for our own universe -- the physical constants at the extreme edge of the expanding universe aren't the same as those at the "center" (wherever that may be).
I've read science fiction and fantasy my entire life; I have no problem wrapping my head around alternate modes of reality. What I expect from a literary creation of an alternate reality is that it will be internally self-consistent so as to be effective at telling a good story. And as a form of literary creation (albeit one with extra constraints), MMORPGs are not exempt from this expectation. If they have any interest in telling a good story, a reasonable attention to internal consistency is mandatory.
Where this gets a little funny is that caveat about "extra constraints." That being, these MMORPG things aren't just literary creations -- they also need to succeed as games. (I think perhaps people don't appreciate just how hard it is to do one thing well, like make a fun game or tell a good story, much less do both at the same time.) If you see MMORPGs primarily or exclusively as "just a game," then sure, you probably think that caring about consistency is just a waste of developer time that would be better spent adding new kinds of loot drops.
But I can, have, and will argue that to think of MMORPGs as "only" games is to miss a rare opportunity to get in on the ground floor of defining a new art form. MMORPGs are sometimes compared to theme parks because both are about creating a massively shared entertainment experience. What sets MMORPGs apart from theme parks is that a MMORPG can do more; because it's just code and data it's easy to change, giving developers the power to tell a coherent story by defining the world and its inhabitants at will.
So for a developer to pass up that opportunity, for them to always rule in favor of game over world whenever there's a conflict, is to choose not to participate in exploring the possibilities of a new kind of art. Being a part of that process means taking the time to make the world literarily consistent -- there must be reasons why things are the way they are, and those reasons must be consciously organized in order to most effectively tell a good story.
