Norman Davies said this quote

The title ‘Lord of All-Rus'’ did not possess much basis either in history or in current reality. It came into the same category as that whereby the kings of England laid claim to France. In the 1490s, two-and-a-half centuries after all traces of a united Kievan Rus' had been destroyed, it had the same degree of credibility that the king of France might have enjoyed if, in his struggle with the German Empire, he had proclaimed himself ‘Lord of all the Franks’. By that time, it conflicted with the separate identity that the ‘Ruthenes’ of Lithuania had assumed from the ‘Russians’ of Moscow. Indeed, it all seemed sufficiently unreal for the Lithuanians to accept it as a small price to pay for Ivan’s good humour. They were not to know it, but they were conceding the ideological cornerstone of territorial ambitions that would be pursued for 500 years.