Your main reason doesn't make sense. It's not like whoever initiates the walkover gets the 48 minutes. The opponent does. So you can't just say 'oh I'm going to not set up my lineup so I get 48 minutes'. It hinders your team while potentially helping the other team. Potentially being a key word. As GM-Manon pointed out you still can get injured. And it's obviously not just my view since it's been repeatedly discussed in the suggestions forums. You're right on one thing though, they will never change it. They are way too reluctant to make changes in general, hardly any non-minuscule changes have been made since season 6 so..
Anyway I'm still sticking by what I believe, and that is it's not fair for you to suffer just because the other manager doesn't play this game anymore or was just too lazy to set up a lineup. Being active in this game should be rewarded, not the opposite which is now the case.