At most of the weddings we go to most men wear morning suits- the weddings tend to be formal church + marquee.
Do you mean, should your H wear one as a guest or should you have it as the dress code at your wedding? If the former, I'd ask if you're not sure- I wouldn't personally want to be the only one in a morning suit (or worse, be in one if only the groom and BM were), unless it's obviously a relaxed affair in which case lounge suit is better. If the latter, I wouldn't impose a dress code that your friends will have to shell out to follow. If you just mean that he wants to wear one himself (as groom), why not, unless it's otherwise a very informal do? Do get him to wear a tie rather than some awful cravat though- it's not A Christmas Carol.