If you are going to use these on a computer at all you need some sort of high refresh mode. Things like scrolling and typing are just way too annoying without it.
In fact there already are some projects of eInk-orientd OSes (e.g. MuditaOS). I don't know how good they really are though.
I hate scrolling and hardly ever scroll really - I just use multiple vertical displays to fit every page fully, only switching pages. Surely this whole discussion thread can't be fit in a screen but I'm perfectly comfortable "scrolling" it with PgDn.
I'm used to slow-response typing (waiting for seconds before a word I typed appears when using modern software on old PCs). In fact I don't even look at the screen when I type until I finish a sentence - despite typing fairly fast I have a habit of looking at the keyboard. I don't mean this is a right way to type yet it proves seeing characters displayed immediately is not essential.
Messenger apps even have separate panes for displaying message threads and for editing the message you are going to submit - I could put these on separate displays (if the apps would allow moving panels around the way classic desktop apps did).