Thinking about this, I find Type 3 bodies requiring more suspension of disbelief than the magical underwear.
This is true of every body mod for the ladies of the Fallout Universe that I've ever seen. I mean, I have poor sight, but I don't need models to have
hippos where
hips should be in order to perceive femininity, they tend to have all the tact and subtlety of a train wreck. On fire. Being salvaged by little green men in flying saucers, using tractor beams.
I'd love a body that sticks to the vanilla type, to the be honest, but does it in a more detailed away. The vanilla bodies look more like real world people. In the real world, not every lady you'll meet has a perfect hourglass figure, and not every bloke you'll encounter will be a body builder (with an incredibly hairy chest, in some instances), and perfectly toned. The vanilla bodies are more 'average', they look like they've had wear and tear, they look like they're used to hard work more than exercise. They look more like what you'd expect to find in a post-apocalyptic wasteland.
To be honest, seeing a wasteland filled with supermodels would make me want to gouge my eyes out.

So I can understand how it's immersion-shattering for you, I really can. If body replacers did 'perfectly average', I'd be all for them. But they don't, instead, we have Herculean and Seductress, pretty much, depending on gender. If anyone's aware of one that has slipped past my view though that does fit into 'average' as I've described, then let me know and I'll give it a shot!