Hey Chris...
First off, you seem like a very cool, supportive wife, he's a lucky dude! Like GBORN, I'm bald by choice, so I don't know exactly hoiw it feels to "need" to sport the bald sly look..
I chose to be bald about 12 years ago, to the surprise of my girlfriend (my wife now) at the time...she kinda understood, but thought i'd grow it back eventually...didn't grow it back until right before we got married...after 2 months with hair, she said, "You know what, it's just not YOU with hair, shave it!".... I was bald for my wedding (thankfully) and have been slick and smooth since...when the subject comes up with your husband , remind him, not only balding guys choose it as a lifestyle these days... some dudes with hair WANT to be bald too!
My boss though is young and totally balding and his wife WANTS him to shave it smooth also (for years now), he buzzed it to a #4 once, said he felt sick about it, like he gave up or something...and has actually grown back his faux-comb-over!!!! he's a young dude, in a young industry...with bald by choice dudes all around him daily and he CAN'T do it, so i understand your husband's hesitation...he doesn't want to give in just yet...there is no going back in his book...
Hang in there and maybe suggest it initally as a kind of (and i don't mean this disrespectfully) sexy thing between you and him...maybe offer to do it for him and tell him how much you DO like totally bald men ect...maybe he'll go for it...again,say it respectfully!
Good luck and let us know what happens!