Following the end of the Cold War, there was much discussion concerning the point of NATO. In the event, it was reinvented as a means of reducing Russia's reach on its western frontiers and seeking to isolate it. Its former East European client states were admitted to NATO, as were the Baltic states.
NATO was built to counteract the Soviet Union in its day and time. At this point there is no threat coming from the Soviet Union, because there is no Soviet Union anymore. And where there was the Soviet Union once, there is now a number of countries, among them the new and democratic Russia.