This sounds terribly logical which is why people are complaining

We have the delightful arrival of a government plan that is actually sensible. That being, of course, why it's unlikely to get through and also why there is much a'wailin' an' a'cryin' about it all. For to some people government isn't there to do sensible things it's there only to protect their own interests. The sensible thing is that places which have planning permission will be regarded as having planning permission. Which, given that the point and purpose of having a system of planning permissions is to indicate where people have permission to do the planned thing sounds very reasonable indeed to us:

Tens of thousands of new homes in greenfield areas in England will be given automatic planning permission amid fears that communities will have inappropriate developments forced on them. Ministers have quietly given developers the right to be granted "planning in principle" in areas that are earmarked for new housing schemes.

So there we have it, that is the change being mooted. That places where it has already been decided that houses should be built should be regarded as places where houses can be built. There are, of course, those a'wailin' an' a'whinin':

Rural campaigners said the new powers will restrict the rights of council planning officers to ensure that the design, density, size and location of homes is in keeping with local areas. Shaun Spiers, chief executive of the Campaign to protect Rural England, said: "“The country needs more house building, but the way to achieve this is through well-planned developments that win public consent. Imposing development without local democratic oversight is a recipe for discord.

No Mr. Spiers, it is precisely you and your ilk that this change is meant to defeat. We do not need that sort of detailed planning: just as we do not need Whitehall deciding how many tonnes of steel are made, of what type, and by whom. Nor wheat grown, shoe styles determined nor how people coif their hair, all things which various governments at various times have tried to dictate.

We ourselves favour no planning system at all, the complete abolition of the Town and Country Planning At 1948 and successors. But if that's not going to happen then we're quite happy with the idea that the level of the current system where the NIMBYs and the BANANAs stick their oar in be abolished. We're perhaps BANAs, build anything near anyone, but in the absence of that we're quite happy with the idea that if a piece of land has permission to build upon it then the general assumption is that permission has been granted to build upon that piece of land.