After all the backlash, Bethesda has announced they will make logging in optional in a future update for all three titles:
Update on our new classic DOOM releases:
The BethesdaNet login requirement was included for the Slayers Club, to reward members for playing the classic DOOM games.
The login should be optional, and we are working on changing the requirement to optional now.
— Bethesda (@bethesda) July 27, 2019
What do you think?