That seems like a weak argument. It's still going to do the wrong thing when the local machine has a 10.x.x.x address and the local server has a 172.16.x.x address. The right solution is for the local admin to have the local DNS server return only the local address for local clients.

getaddrinfo() is also a much more complicated function than gethostbyname(). If you need the extra features, fine. If you're writing new code, fine. But going back and trying to update existing code is just going to introduce new bugs.