i already half full map unlocked,campaign unlocked on D4 base version, do i need to play through the Vessel of hatred campaign to play end game online?

No. You do whatever you want with it once bought the game.

thanks bud nothing unlocked behind the vessel of hatred campaign? i just want to grind end game i hate questing lmfao

You don’t have to quest for leveling. Only quests you have to do is the class one that grants you class’s unique power. Other than that, you can simply farm to level and get to end game stuffs.

NO is the quick answer. You can skip campaigns.

You will get achievements/cosmetics (titles etc.) from campaign and a pretty epic lore.

negative, skip everything campaign wise.