I'm with you. I think that using CPAN modules for converting dates, XML etc. is preferable to rolling one's own regexes. There is just too much opportunity for mischief with malformed dates, leap years, invalid input, etc.

Personally I prefer Date::Manip for these sorts of tasks, but to each his own. Or a Serge Gainsbourg said, "A son gout est l'appetit, l'appetit est a son gout." (One's taste is according to one's appetite, one's appetite is according to one's taste.")