It is still given in classes because it is the base of Networks! I dare those who say bads about this little movie to identify the OSI layers in this video! There are only two layers that I couldn't identify. It's a good practice! You need to learn the base to be able to improve whatever it needs to be improved! That's like you are gonna vote for a politician, but you don't know if he was a killer or just a normal person, then he was a killer, you vote for him and he starts a war from nothing! It has nothing to do with Networks, but you need to know how it was built, the history and techniques, from the past till now to be able to handle any issues or even to build a better solution for the future! If you think that studying just what is in use now will supply your needs, you better review your concepts buddy!