Swapping RAM chips on a board is something a tiny minority of customers would want to do.

Giving that tiny minority that freedom, at the expense of opening up the vast majority of other customers to potential problems, is a dumb choice to make (IMO), which is why they didn't make it.

On the topic of choice, perhaps YOU could choose to buy a thing that does what you want, rather than expecting every product to cater to your needs, regardless of whether it makes sense for it to do so or not.