Your daughter made an excellent point here. It was probably impossible, even for a legendary designer like Trisha Biggar and her crew, to make so many different costumes that every character could change styles like Queen Amidala. But I agree 100%, they change planets like their socks, but not their costumes. All companies that produce merch of the characters would've certainly welcomed more variety as well! $$$
Costumes have been expensive ever since - also in classic Theater. And George wanted to make a space opera with poignant destinies on a limited budget. Then customizing enters the stage.
Really nice customs here - I could well imagine an adventure of the OT crew in these outfits! Oh, well. This will never happen...