The problem is if you do just let it rip, you stand the chance of overwhelming hospitals and killing or incapacitating health workers, thus making things a whole lot worse. Plus, you're still going to have to isolate the most vulnerable- particularly in care homes- so they're going to be in the same situation as they are now. That's before you even consider nasty stuff like long-Covid, where a significant percentage of people are still ill months after the initial infection.
As for the rules, they're a hodgepodge of sensible and stupid ideas and seem to have been cooked up on the back of theoretical models and actuarial figures. To take one example, either close pubs completely and compensate them financially or let them stay open as normal. Trying this ridiculous middle ground of shutting at ten is the worst of both worlds with a load of unintended but entirely foreseeable consequences- something this shithouse of a government seems very adept at doing.