Because it is useful.
- If you are studying at a Slovene university you will most likely work in the Slovene environment after graduation, therefore you will need to speak Slovene at work.
- Although most Slovenes have been probably speaking Slovene since their childhood, they still have to learn Slovene professional writing, ways of expressing, and terminology somewhere. The easiest way to do that is to study in Slovene.
- If Slovenes only used English for your study and work, they could find themselves in a very embarrassing position when having to explain in Slovene what they're actually doing.
- Some study subjects are more dependent on language than others. For discussions of Slovene history, society, culture or language, the language in which they are held is much more important as, let's say, for those about mathematics or chemistry.