A purely national and political affair
There is nothing wrong with referring to Serbian, Croatian and Bosnian as separate languages, in the same way as Hindi/Urdu, Swedish/Norwegian, Flemish/Dutch is. But it is a purely national and political affair, often (but not always) based on a desire to be distant from a neighbour. But linguistically the difference between Serbian, Croatian and Bosnian are too weak to constitute separate languages. It always comes back to the bottom line, however much esoteric, linguistic sophistry is employed: that language is about communication, and nothing more. If Serbs, Croats and Bosnians, despite a few lexical and grammatical differences, can understand each other at every level and complexity (and they can because I've heard them), then in all but political respects they are speaking the same language. The differences between German spoken in Austria and Germany, or that between US and UK English (and even within the UK itself) are the same or even greater than those between Serbian, Croatian and Bosnian.
Sent by: T Payne