You miss the point though - if symptoms for the majority are now no worse than a cold, what does it matter if it spreads across the whole workforce? Cols etc. have been doing so for years.
Once the disease is sufficiently mild enough to enable the hospitals to cope, it would be appropriate to reduce/eliminate the isolation period, as well as other controls. The question is are we really at that point now?
Omicron may represent the point of acceptable mildness right now or in the New Year, but it is too early to say. It may be that we need to wait for another milder variant to come next year, or maybe not.
The isolation period will certainly go from 7 to 5 days eventually, before likely being eliminated altogether at some point. Relaxation steps in all policies need to be made in tandem with the reducing effect on hospital capacity, and I think that is loosely what's been done.
The trajectory at the moment looks like it will become a very mild virus and effectively just become part of the package of viruses that make up common colds. The question is how quickly can we allow it to get to that point without overwhelming - or exacerbating existing issues such as poor waiting times in - the health service.