I don't think there's any denial about the cases being mild for the most part. The issue I think is one of timing and communication....
Realistically yes, it makes sense to try and stop everybody getting it all at once, thus slowing the spread somewhat. So even though the cases are more likely to be milder, the effect of a huge swathe of people getting sick is one to limit if possible.
The issue is they couldn't say it that bluntly.
The day after the Xmas party videos, when public trust is at an all time low, if they had said "..it's probably a mild disease but we need to just slow it down a bit, so please put a mask on and take more tests", pretty much nobody would have listened....
IMO this is why there's barely any major media talk of the SA real data, and more about the "worst case" and 100,000s of deaths etc etc, it's an exercise in scaring people into compliance, even when the Plan B restrictions are justified.
I don't think there's going to be a huge increase in deaths, partly because increased booster jabs will have an impact, but also because Omicron doesn't look to be as severe.