I think there were national planning guidance changes in the 1970s, which did this.
Curvy cul-de-sacs and so on provided more variety, less speedy traffic and allegedly less burglary.
But it also provided more social isolation.
One thing I always notice about proposals from that time is the INTERNAL plans of the homes - room sizes and functions and so on. The EXTERNAL shape of the blocks and units were merely a result of that.
Nowadays it is the other way round. It is always an outside view of some stack of rabbit hutches that appears in the papers.
I think the windy layouts are a biproduct of trying to look like naturally evolved villages rather than planned streets. My estate is windy because the existing roads were already windy country lanes, and many new estates try and recreate that, especially with the new (good) trend for village greens and parks. And while it takes up more room it can make places look nicer (subjectively). Not being able to see a hundred houses ahead of you makes a place feel cosy and friendly, and cul-de-sacs mean no unsolicited traffic. There are reasons people prefer them. Straight roads also mean faster speeds drivers are able to reach, a lot of curviness is to try and stop that. It's not the best use of land perhaps, and developers often go too far, but there are reasons people like that.