One dimension most mediæval performances ignore is duration. A lot of mediæval texts are very long, and to a modern ear, repetitive. We aren't accustomed to that sort of experience in something presented to us as a song (though people will spend even longer periods involved in other kinds of narrative, like a video game or audiobook). Performers will usually cut drastically.

How do you persuade people to devote as much of their evening to following a mediæval narrative song to its end as they would to getting to the next level in a game? Just putting the thing on record and hoping people will stay interested doesn't work, if the one example I can think of is predictive - Andy Hunter's performance of the late mediæval Scottish epic "Graysteil" is the most bum-numbingly dull experience you could hope never to suffer through. Anything that takes up that much of your time needs a LOT of external context to keep you interested.