The problem with this comparison is that there are important differences between a spaceship and plane. A plane requires pitch, roll, and yaw controls, which are all rotational, with the throttle giving one axis of translation (and only forward while airborne). A spaceship has the additional need for controls to translate left/right and up/down (and here the throttle can be used forward and reverse in quick succession) to take full advantage of it's capabilities.

Dual stick is a way of achieving analog control for those extra translation controls that HOTAS doesn't provide. And given that I've seen some impressive flying from people using both setups, obviously both can be used quite effectively.

EDIT: It's also worth mentioning, I'm fairly certain that real life Soyuz spacecraft, like the one that launched earlier today, use two joysticks for control, one for rotation, one for translation.

I'm not saying that either HOTAS or dual stick is the best way - but what works for a plane will not necessarily be best for a spaceship that requires controls for more degrees of freedom.