Interesting. Do you think that perceived/projected "snobbery" on both sides might be responsible for the separation of the terms?
I don't see snobbery on either side, to be honest. What I see is that your typical American has a very restricted understanding of religion that is a byproduct of widespread lack of education or exposure on the subject. People's understanding of religion in this country tends to be informed only by what they were raised with. This means your typical American believes religion has to have certain characteristics that don't represent the full breadth of the world's religions today or throughout history. What it really boils down to is the "spiritual" crowd reject the mainstream norms of the traditional Western understanding of religion without recognizing that what they're doing can be (and is) called religion too. What they're doing is rejecting institutional/organized/dogmatic forms of religion for something more personal and relevant in their lives. That's still religion.
There are better voices than I to remark up on the causes behind the recent division of meaning between these two terms. It's been many years now since I've read this work, but this book (amazon link) is worth a gander.