Of all the strange new worlds Star Trek explores, it's the non-capitalist future, without poverty, that people have the most trouble with.
And I don't really buy that whats objectionable is the lack of explanation. Its the boldness of saying humanity has to grow up to reach the stars. And that growing up means going beyond religion, nationalism, and capitalism.
What is more likely is a mass extinction, huge population loss, and crawl back out of another dark age. But I prefer Roddenberry's worst ideas to more of the same.