It is my understanding that the Welsh warmed up to the Romans over time. The Romans let the Welsh govern themselves and practice paganism and kept other barbarians from raiding. In turn, the Welsh allowed them to coexist peacefully and helped keep the Irish at bay. The villa probably belonged to an ambassador.
Definitely. There was internecine warfare among the Gallic / British / Gaelic tribes before the Romans got there, and having an outside authority as a referee (not to mention the economic boom, and of course, becoming a minority in much of the island; the Romans brought in and settled various auxiliaries pulled from vanquished invading tribes, such as the Sarmatians) was a welcome change. There had been an uptick in the population of Britain, as there was generally in Europe, due to the Roman warming period (climate), then the climate cooled and the attractiveness of Britain faded a bit. It was still a more popular destination than most of Gaul during the 3rd c, when the Empire appeared to be falling apart. The cooling brought a steady stream of (basically) refugees down the steppe, and whatever Roman character had existed in the cooler parts of western Europe dwindled to architecture. Even the Roman army regulars had ceased to be even Italian by descent. The Roman Empire was the place to live for a lot of people, but they weren’t exactly popular neighbors, were never properly or systematically assimilated, and, hey, wait a minute...