Comment made by: xmlblog
Also, from an aesthetic(link: 1) point of view adding a type predicate (ex-info?) for a pretty important core Clojure abstraction that already has a constructor (ex-info) and an accessor (ex-data) just seems to round out / complete the API. Not sure how that compelling you or Rich might find that argument, but I figured it couldn't hurt the case.
(link: 1) My sense of aesthetic here is colored by some of the ideas in Mitch Wand & Dan Friedman's Essentials of Programming Languages.