Chromatic aberration is one reason why you don't see many large/professional telescopes use lenses. Another is that enormous, thick, heavy lenses aren't very practical. This seems to solve both problems.
There are a lot of reasons telescopes use mirrors over lenses, only some of which this resolves. Also, will Capasso's work scale to the meters wide telescopes that you want so as to collect a lot of light?
Telescopes also require high optical efficiency, because the entire point is to capture as many photons as possible. It seems likely that any application that uses diffraction has higher-order effects that send part of the light in unwanted directions, even if there is a distinct focus.