I somewhat agree in that it's the main draw as it's what makes them unique. However, if she's a proper futa, even if full package, she'd have a pussy for you to fuck. And if you were to spend time with a futa long term she'd probably want you to penetrate her every once in a while maybe even right after pounding you. Another reason to give her a dick is to feel just about very possible pleasure your body can feel while making the experience more mutual and organic. So there's that too in place of just dominance.
Anyway what would be your ideal relationship with a futa? I like hard dom stuff too.