Would it be odd or ok for a man to change his surname to a hyphenated one after marriage?

My friend is going to get married next month and she wants to keep her last name (Montes) and hyphenate her husbands (Romero). And when they have kids, she wants her kids to have the hyphenated name: Montes-Romero. Would it be weird and completely against tradition if she asked her husband to change his last name to Montes-Romero? That way they would all have the same last name. Or it it more appropriate for her future man to keep his name as it is?