It's not necessarily a matter of styling or being "out of date". Different radio/telephone systems in today's cars may (?) sometimes need different antenna types. A mast-type may be best for some functions, while a shark-fin is better for others.

However, one thing we did learn, decades ago, when GM tried the small antenna wires buried in the windshield, was that that system basically didn't work. It not only gave rather poor reception, but also increased the price of windshield replacement/repairs. After only a few years, GM went back to regular masts.