People think of themselves and their situations as normal, and anything else as "OtHeR". Tall people hear others remark on their height so much they know they're tall, but they subconsciously still think of the rest of the world as short. Identifying with folks who are OtHeR is mental work, and people tend to be lazy. It's tricky for instance to write nonhuman protagonists so the reader sympathizes with them, particularly when the bad guys are human. Cherryh's Chanur books succeed with the Hani, but in some ways her Hani are more human than the humans :-). When the hero sides with the good aliens over the evil humans you still have an underthought of "traitor to his own kind!"

So to focus primarily on the potentially fascinating nonhumans places a writer in the spot of turning off a lot of his readers. If his point is to tell a certain story, and it could work with humans ( or his own ethnic group, or language, or socioeconomic group) then to cast the story in a foreign setting is to obscure the point of the tale. That can work in reverse - to make a statement that will be hard for the audience to accept, one can set it in a strange place with unfamiliar people, and either reveal at the end it's ReAlLy *YOU* I am scolding, or better yet, leave it to the reader to draw inferences.

A creative setting can be a delight, and can allow one to explore situations normal to (say) white middle class Protestant English speakers... Particularly if one accepts a smaller than otherwise likely audience;-). Hey, if you're Already in the niche audience of fantasy or science fiction, maybe you're improving your audience -- among those already interested in otherness! The first necessity though is a good story. All the ingenious Worldbuilding possible, all the creative constructed language aside, I still won't care about a story (or map) if it isn't crafted well, plotted well, characterized well.

Perhaps as a generality it's good to suggest authors (etc) work with what they're familiar with, to first home their craft. But I'll cheerfully acknowledge if it is the attraction of a unique setting that draws you to create, then dive into the odd races and wierd worlds from the start! Just be ready to write and write and write and file away the first hundred of what you're making, till you get good enough to get people engaged with your UV-seeing, radar-communicating, argon-breathing centauroids :-). It's only an Isaac Asimov who typed finished copy from scratch. It's only a Tom Clancy who sells his very first novel. If you're like me and music - I assert I play strictly to amuse myself and annoy the cat - you can have a lot of fun with what you create, and if others happen to like it, fine. If not, also fine :-).