Frankly, I do the swapping because I own a few different phones and for various reasons, like the idea of being able to switch between them at a moment's notice. I'd explain further, but I doubt it would make much difference to you, as you obviously have no need for this sort of thing yourself.
What your attitude is suggesting is similar to that of someone owning 2 cars, having to contact the dealer each time he wanted to use one or the other. Would you accept that? No, a phone is not a car, but please try and understand that not everyone uses phones in the same manner as everyone else and that certain phones are sometimes more appropriate in certain situations than in others.
Wasn’t there a limit on how many times you can swap e-sims online? I think it was two or three times a years.
I’ve never heard of any provider allowing manual switching online on a constant basis.