What you wrote suggests the data will bias predictably, which matches my understanding.

Reporting biased data as the default because the bias compensation is already built into the audience seems like a weak argument for not improving.

They can provide for the continuation of data visibility/granularity by releasing the prior numbers as previously calculated and at the same time changing the calculation of the headline number to be better compensated.

The simpler argument is that changing it at all will result in a negative step change in the reporting that no one wants to take accountability for.