The rise and success of cruft-stripping-as-a-service offerings like Readability, Pocket, Instapaper, etc., seems to indicate that a not-insignificant segment of consumers think that a "decent UI" is _less_ UI.
Simply having a consistent typography, font selection, size, and readable contrast is a huge benefit. Web design isn't the solution, Web design is the problem.
(And asstasstic browser defaults is another problem: why an absolutely unstyled page cannot be perfectly readable and acceptable is a huge flaw. I blame the browser vendors and W3C for this.)
A tool which manages a large written archive is another hugely useful aspect. Tabs and bookmarking both suck.
Also: best I can tell, Readability seem to have died so far as any visible development or company activity goes. There's been none in years, though the service itself works for now. I'm in the process of moving 2000 articles to Pocket (Instapaper lacks necessary features IMO).
It's worth noting that Pinboard.io itself addresses some of these needs.
Otherwise we've had RSS readers and "reader" mode for browsers for a long time but they dont have significant usage.