What did the Romans ever do for us?

When I walk, I walk for a variety of reasons, it's health and fitness, for the hound, to escape, to think, to connect with nature or to connect with our past. If I'm lucky, I can tick several of those boxes in a walk, and if I'm really lucky I can achieve all of them. Today I was really lucky. Cranborne Chase the destination, our route, a stretch of the Acking Dyke, a Roman road constructed shortly after the invasion of 43AD by the Second Legion Augusta, and which after all the intervening years still remains remarkably well preserved in places. Musing on the Roman road, the ''What did the Romans ever do for us?'' sketch from 'The Life of Brian' came to mind. I thought of the many technological advance the Romans had brought us which faded, along with the Romans after their departure in 410AD, all eventually to be completely forgotten. And asked myself, how does that to happen? Why would a people allow that to happen? Why wouldn't life just carry on as it was, how did they just stop living in one set circumstance, opting instead for a far lesser ones. There's evidence of deserted villas being squatted, though not inside, rather shanty shacks built against the outside walls. We stopped building in stone, building roads, maintaining infrastructure and buildings, the urban population left the towns, the quality of our wares deceased, and industries collapsed, institutions too. Why? Why turn your back on advancement wholesale. Did they fear Roman influence, was it superstition and beliefs or was it out of disdain for the colonizer, the outsider? Even though those colonizers, who'd come from across the known world, had been here for nearly 400 years by then. Whatever it was, it was self defeating, an act of cultural, economic and technological devolution, which took us centuries to crawl out of. Of course, we didn't really need to take that path. We chose to. That got me thinking about Brexit, is 'cutting our noses off to spite our collective faces' a particularly British/English thing? The comparison is compelling. I think, even though the Romans left us, and this time it's us leaving Europe, the end result will surely be comparable...degrees of cultural and economic collapse.  I'm all for Living History, although this is taking it too far!