As for hyphenated last names, how do you carry that onto the next generation?
Say, if Mary Smith-Jones marries Harry Johnson-Brown, is their child going to be Matthew Johnson-Brown-Smith-Jones? Then what if HE married a girl with a hyphenated name and they decided to carry on the tradition ? OK, I'm joking but it COULD happen.
The other funny thing about hyphenated names is when the two names just either don't go together or make a funny phrase. I personally knew of an English girl whose last name was Buttolph (pronounced, I assume, butt-off or at least it would be here in the States). She married an American guy with the last name of Cutter. Their wedding announcement was in the paper the same Sunday as ours. I'm assuming they didn't hyphenate their name because it would have been Cutter-Buttolph. That would have been hard to manage on a day-to-day basis. "Hello, I'm Misty Cutter-Buttolph, here for my girdle fitting...."