I would also suggest that if people want to continue to discuss changing boob size or other elements of bodies, we take it out of this thread so it doesn't derail or distract from the topic here.
Fat bodies follow the same reasoning that breast sizes, making a fat body would mean they have to change every armor model in the game like they did for the beefy Halsing body and they ended up implementing because they already had part of the work done, adding a fat body would be an undertaking for a DLC feature I would guess. And if that is the case I don't know if they would put resources into that, it would also depend on the pricing of the DLC and other stuff. It's more complex than it seems at first glance but more customization options is always a win in my book.
The only ''issue'' I might have is that these customization options more often than not only include one side of the spectrum, meaning genital swaping being ''more important'' for representation than different breasts sizes (last comparison/example using breasts I promise lol). But I also acknowledge the fact that one is way more cheaper/easier to add than the other while also being more impactful in terms of PR. Is like adding the they/them pronoun, it's easy and cheap, sure you need to add some extra lines into the game but it's much cheaper than doing separate trans characters fully voiced and with full narrative interaction and plots. It's an easy way to please part of the community.