Yes, but my point is why even go for that big B's then? Obvious answer. And why couldn't they have made smaller or used textures to make them big like they did with the backpack? (same answer) What about the shape of the other body parts etc.
So my point of view stands. I don't think it was just due to technical limitations. Maybe they played a role, but it surely must have been a deliberate decision to make them like that to a large extent.
(I'm gonna guess we're both guys, considering our ability to make a conversation about boob size into a serious and almost scientific matter of great importance)
They were allready so small that they looked very pointy. If you want to have more roundness in a smaller area you need more polygons for your wireframes. Thats why charackters today have more polygons in their faces than they had at that time for the whole body. And more polygons making up one breast than they had back then for their faces.
Nevertheless, im sure one can reasonably argue that if big breast were universaly seen as negative (i personaly prefer them smaller. Ideal size 2 hands full imo.) they wouldve worked on a better solution.