I agree that your setup would be perfect, but the reality of the situation is that it depends on the engine and how much time the programmers/artists/whatever have.
Like if the engine doesn’t support dynamically resizing equipment, then you have to make every single piece of equipment over again for every body shape. That is a potentially massive amount of work, even if there is tooling that will automate most of it and only require retouching. There’s only so much time in the day, and every hour that people are working on this is an hour that they aren’t working on building more levels or adding more systems, etc.
Is it better to have “Body Shape A/B” or “Male Body / Female Body”? Because those are the options that are the same amount of work.
It would be better to have a ton of body options. It would be even better to have sliders and have everything adjust itself to fit whatever shape you make. But both of those options take time to work on, and time is money.
I don’t think it’s fair to call (for a specific choice) BG3’s developers lazy because they only have 2 (or 4 for some races) body sizes. They are just optimizing their time investment.