I was initially, somewhat naively, supportive of the regional lockdown 'tier' system which targeted COVID 'hotspots' and released areas with low instances - for the very reason that you are raising RP, meaning only the severely areas were locked down.
However, whilst that system might have worked in Germany where people are more disciplined, here in the UK it was not respected - people simply journeyed to the closest area which was in a lower tier - which had the OPPOSITE of the intended effect - spreading the virus wider than it would have done had their local area remained unlocked. We simply don't have the resources to police that type of system to ensure that everyone remains within their local area - selfish or ignorant people will always find a way to bend, bypass or break the rules - in fact, for some it becomes an exciting and 'naughty' challenge to try and do so.
Having said all this, I think that given our vaccination programme seems to have been so successful and all 'vulnerables' and (willing) people over the age of 65 have been vaccinated - and these groups made up over 90% of the COVID hospital admissions (so I heard on a TV news show) then I think that keeping the country in lockdown, with all the economic and social damage it's doing, is now a disproportionate 'blunt instrument' response to what is a shrinking issue.
Open the country up now I say - and if people who have refused the vaccine get sick with Covid then they should take their turn in the NHS treatment queue alongside Cancer and other illness sufferers (who one assumes will have been vaccinated as 'vulnerable')