I will try to build further on those two good answers.
Indeed, it's very problematic that the citizens of a country in which people pay with euros need visas to travel to the European Union.
Beside problems with the European Union and NATO member states, there are also still problems in Kosovo itself. Kosovo had a good start in 2008, when it became independent, in being able to build brand new institutions that did not have all the heritage that neighbouring countries were carrying. Still, politicians in Kosovo lack any will to move forward. There is still a problem with corruption and clientelism. That is a large blockage in making progress in democratic reform.