And to answer your question... we hire both. Some designers on the team code, some do not. If they're good at what they do, you'll find (or they'll find) where they fit in.
Like I said, the more a designer codes, the less they design. If you really need help and you can't find a "unicorn", maybe you should consider hiring both a front-end engineer and a designer? If you don't think there's enough design work to go around, hiring a design contractor (and a full-time front-end engineer) might be a better route.
And to answer your question... we hire both. Some designers on the team code, some do not. If they're good at what they do, you'll find (or they'll find) where they fit in.
Like I said, the more a designer codes, the less they design. If you really need help and you can't find a "unicorn", maybe you should consider hiring both a front-end engineer and a designer? If you don't think there's enough design work to go around, hiring a design contractor (and a full-time front-end engineer) might be a better route.