The problem is that the higher-level abstraction is broken. Specifically, the abstraction provided here is "extract an integer of unspecified size and endianness from a byte stream" (note that the size of short isn't guaranteed to be anything specifically, other than 2 <= sizeof(short) <= sizeof(int)). And ntohs is another abstraction which amounts to, "make the endianness correct for the current system, assuming that it was originally big-endian". Not that it doesn't work - it's just not well-designed, and too easy to use incorrectly.

A proper abstraction is the one where you specify both the size and the endianness at the point where you extract the value - i.e. where you just call a function like read_int16_be(byte_stream).