I think a couple of points are being missed or mis-interpreted. Omicron being milder doesn't mean its 'like the flu' or people don't end up in hospital and dying. Its the smaller percentage of a bigger number issue again.
Omicron hospitalisations are said to be about a third of Delta according to the latest reports I can find. But the rate of infection is so much higher that is offset. This is where the R number comes into play. If you read up on that you will see that even very small changes to the R have a large impact. It therefore follows that if you can make a reduction to the R, no matter how small, it will within a couple of weeks have a significant impact. Scrap isolation and the R rate will undoubtedly go up and we could quickly be in trouble.
As ever there's no quick fix, you can't change one thing and solve the problem. The NHS is, at least in part, struggling due to years of underfunding. How is a service that is termed as in crisis every single winter supposed to cope with the slightest thing that increases demand? For years its been promises of new hospitals, more beds, more nurses, more GPs but here we are with thousands of unfilled vacancies.