I don't "like" RTF--I just already have a lot of stuff as Word docs & html files, and converting to RTF is insta-quick; converting to other things takes a bit of time & thought.
I've got somewhere between several dozen a few hundred fanfic stories collected, some of which I want to re-read, some of which I just saved out as html (usually as LiveJournal posts) for later reading... RTF is the quickest format for me to throw them into for putting on the reader.
I want Contents links & bookmarks... but after dealing with some Gutenberg files, I consider them perks rather than necessities. (I've installed Calibre & will start figuring out how to work with it. Can't directly go from my downloaded files to it; the downloads include header & sidebar stuff that needs to be removed.)
As to why I'd want to convert from LRF... because the Reader isn't the only way I read ebooks. Don't have any particular plans at the moment; just want to know whether books I acquire as LRF are convertible, or if LRF is an end-result only (like eReader .pdb files) and if I want to tinker with the shape of the content, I'll have to acquire it in another form as well.