Capturing capitals was almost always the primary goal: it’s a symbolic act, and they are typically the centers of power, either economically, culturally, politically, etc. The reason the Europe board is set up the way it is now is because Hitler ignored the more strategic goal of crushing the UK at Dunkirk and instead went towards Paris (no UK troops in the Normandy territory). After the mistaken bombing of London, Hitler continued because he thought it would wear the British down, and England retaliated by sending a bombing mission to Berlin, even though it was mostly useless. The invasion of Poland was focused mainly on capturing Warsaw, and the Polish fought very hard to defend it. And I thought it was common knowledge that if Hitler had not called off the Moscow offensive to divert to Stalingrad, the Germans would’ve triumphed because of how the Russian society, military, communication network, etc was set up (all centralized to maintain control).
So, I have no problems with how capitals are set up now. Is it a more interesting goal to capture all the useless East Russian territory? I don’t think so. And as others have said, you don’t need a capital capture to win the game. Maybe it’s more efficient in terms of number of turns to destroy the enemy, but it’s always the most heavily defended territory and requires the most IPC investment.