Note that the two deployments were of different components.
Basically, imagine the following scenario: A patch for a critical vulnerability gets released, during rollout you get a few reports of it causing the screensaver to show a corrupt video buffer instead, you roll out a GPO to use a blank screensaver instead of the intended corporate branding, a crash in a script parsing the GPOs on this new value prevents users from logging in.
There's no direct technical link between the two issues. A mitigation of the first one merely exposed a latent bug in the second one. In hindsight it is easy to say that the right approach is obviously to roll back, but in practice a roll forward is often the better choice - both from an ops perspective and from a safety perspective.
Given the above scenario, how many people are genuinely willing to do a full rollback, file a ticket with Microsoft, and hope they'll get around to fixing it some time soon? I think in practice the vast majority of us will just look for a suitable temporary workaround instead.