Thanks for the link. I note considerable discussion of risk-sharing in the consultation, presumably to protect those who made poor investment decisions (or the managers took all the money in admin costs).
It wouldn't be easy to shift out of defined benefit into defined contribution.
One of the shortcomings of many defined benefit schemes is that they have a lot of their money invested in bonds or similar "safe" (but low yielding) investments so there's certainty about having enough money to pay the next 10 years or so of pensions. And, as in the case of HPS, the scheme was underfunded then it doesn't leave a good share of the assets available to be invested for growth.
If I were putting money into a defined contribution scheme then I would be looking for capital growth (which tends to be associated with more risk) and would only consider locking in some of that growth when getting close to drawing the pension.