Thanks! That's useful feedback. Hacklily's audience so far is primarily users who are already Lilypond users, but I'd love to make it more broadly useful.
Agreed. As a lilypond user, hiding some of the extra stuff would be confusing to me. I don't think it would be simple to create a mode for more easy note-only editing.
As context for my comment, I have actually never heard of Lilypond! The "code view" just seems like something I'd export to move to another machine or to send to someone or the like.