According to the story and lore we can't be overpowered and corrupted by the Primals since we have the light of Hydaelyn. Even though we are only one Summoner tapping into more energy to summon Primals that are twice the size of the player wouldn't break game lore since they are not as large and powerful as the Primals summoned by the Beast Tribes. Also the size and detail of the Primals has nothing to do with it's power considering Hard Modes and Extreme Modes and Square already broke lore rules when they had Lightning summon Odin during the Wonder and Lightning Fate.