However, currently the only way to throw a Spear or Hand Axe is to use the Throw Action.
When martial classes get a second attack this will place Strength builds at a disadvantage if the Throw Action doesn't recognize that the character should be able to throw twice.
The reason why discussion went to spells is that from what we can tell so far (speed spell, enemies) Larian seems to be implementing multiattack as an extra full action - so yeah, it is likely that you will be able to throw multiple times per turn. It is other abilities that are not originally meant to be used multiple times per turn that might be a problem.