Hey Graham, thanks for the comment. I read it, and you'd probably be surprised that I agree with some of the sentiment. Some of the components in the Jakarta Commons have problems with API changes after a 1.0 release, but you should know that there is a large very vocal contigent of commons developers who believe that backwards compatibility is of maximum importance. There is a ongoing discussion about package naming, which could address some of these concerns. CLI released a complete refactor in a new package cli2.
But, you are right, especially with the component you mention, Validator. Unexpected API changes can really be a PITA.