So two things. As you see in your list, there are still those normal companions that can balance out the party, and in mass Effect 3 we still have a normal companions again, with James. The rest of the companions are returning ones, who are now high level and have grown throughout the series. Even in ME2, that was the second game. Even if those specific companions are really special, it's more earned because the greater story of the series has escalated, as has shepherd and so the new companions escalate to match.
Second, the entire premise of the game, up front is gathering a team of elite badasses led by shepherd, the ultimate badass. When you buy the game you buy it signing on for that experience. The premise of BG3 doesn't advertise or require these great, high falooting companions. Even Lae'zel, the most basic member of the party acts like she's superior to us in ways that don't make sense for her to stay on the team. Hell, lae'zel even is a refutation of your claim. She's by all appearances a normal Githyanki.
