Most things would benefit from encryption. Even if you don't need integrity protection, and you don't have any need of privacy, and you don't care about authenticating your peers you still want encryption because otherwise middleboxes ossify everything.
If the middlebox can't see inside your flow because it's encrypted it can't object to whatever new thing it's scared of this time whether that's HD video or a new HTML tag.
Not a significant issue in practice as far as I can tell. I deliver text over the internet, and sometimes binaries over the internet, and it happens very fast because there is no useless cruft in the process to satisfy some security twonk's paranoid delusions.
