For a driver, there would be problems getting it to run correctly in 2004 already, since the internal Linux kernel API used by drivers is not stable and changes very rapidly. Unless the driver has been upstreamed, because developers updating the kernel internal APIs also update all the in-tree drivers at the same time.

About leveraging one interface or the other: when you use the glibc interface, you are also using the Linux interface behind it, so a change in either can affect your program. On the other hand, if you are using the Linux interface directly instead of going through the C library, chances are you are doing something unusual, which increases the risk of it breaking by accident. And there are some things which exist only on the glibc interface, like nameserver lookups (getaddrinfo), user database lookups (getpwnam/getpwuid), and many more.