Here are two minor details that have slowed down RSS adoption on the reader side (in my opinion):
- RSS client not shipping built-in with firefox and chrome. It could even have been a permanently pinned tab. Safari supposedly has a built-in RSS reader, never seen it.
- The RSS XML displays code instead of downloading a file. Many more people know how to drag and drop or point to a file, vs the number of people who know they can right click and save any piece of text in the browser to XML.