Perhaps you should be upset because it is the Home Office, not individual Police Forces, that states that home visits should be arranged by prior appointment at a mutually convenient time.
Turning up unannounced may not be convenient, as you may be about to go out, might not be home, might be in the middle of a meal, a bath, shower, inebriated, using the toilet, asleep, or participating in the joy of union with your partner.
It would be better use of Police resources to arrange a visit by prior appointment than turning up mob handed on the off-chance that you're in or willing/able to answer the door.
I've no personal objection in complying with a home visit, and if I'm not otherwise occupied would be happy to show them my empty Gun Cabinet, however, there is a principle at stake here, and the assumption that we might be up to no good after having jumped through all the hoops to be regarded as a trustworthy citizen, what has changed in North Wales to make the Police there adopt this strategy to find crimes committed by the one group they have already identified as being model citizens least likely to commit crime?
Very odd behaviour from NWP