In the barrier block (if I remember correctly from last time I was in there) there is a controlled entry at street level, which takes you into the stairwell, then you go out onto a non-public open terrace/walkway on the other side, then through the front door to the individual flats (some of them I think have private outdoor spaces between the terrace walkway and the flat).
In the Barratt development there's controlled entry at street level, then a non-public courtyard, then controlled entry to stairwell, then door to individual flat.
The main difference is in the nature of the non-public/communal outdoor space - in the barrier block open terraces, in the Barratt building a largish internal courtyard. Both are inaccessible to the public. The question it seems to me, if you are going to criticise the Barratt development and describe it as a "gated community" or whatever, is whether it would be reasonable to expect that communal courtyard to be open to the street.
It's not space that was previously public space, it's not blocking a through access route to anywhere, and if there are bike stores and suchlike in there I can see why you might want entry to be controlled.
It's also not in any way unprecedented or abnormal to have an urban development with a street entrance and private internal courtyard. It's a very common arrangement that you can see examples of in cities pretty much anywhere in the world and from any historical era.
I can think of various types of housing which would have been built with a publicly accessible internal courtyard originally, but to which controlled entry has been subsequently added. Glasgow tenement blocks for example, or various postwar social housing developments. I think I'm right in saying that the controlled entry to the barrier block was added later and that originally the terraces were publicly accessible.
If there are good reasons for social housing to have controlled access and private outdoor communal spaces then why don't they apply to a development like this? What actually is the problem here?