Would there have been less trade? What about technology, was there any major regression? Did the social customs change, if so how drastically? What about political systems, would it have regressed as well?
Lot of parts to this question and I'll do my best to address them in turn.
"Middle class" The middle class as you and I understand it did not exactly exist. There were certainly people with middle levels of income, but almost all income in the ancient world was more unstable than we can really imagine. In patronage-based systems of commerce, a craftsman could easily see sales drop to zero or jump rapidly based on the politics of the local noble classes. Merchants were especially vulnerable to raiding and the constant low-level wars of the region, though these affected everyone. Soldiers/raiders could make a good living through war and banditry (there was barely a distinction), but one bad battle, camp disease, or wrong turning in the desert could mean disaster. Landowners, farmers and herders had some stability, but minor variations in climate hit them hard, and impacted everything around them. In all, society was often right on the knife-edge of subsistence... when all went well, new opportunities would crop up for craftspeople, merchants, and raiders. But when things turned for the worst, the limited demand would throw people into destitution. And this didn't take something like the collapse... this sort of instability was just par for the course for most of humanity's history.
Impact on trade So here's where we start with the actual question, and the recurring answer: "Kinda/sorta." Established systems of trade across the region were in fact throughly blown up. Anything that depended on long established trade nodes was in serious jeopardy from the social collapse. Indeed, most long distance trade was far more perilous. If you had been a merchant before your region felt the effects, things would have been pretty dicey... but if you had been clever, flexible, and very clever, things might have worked out alright for you. In certain (limited) ways, trade became less parochial as a result of the collapse, both due to the kind of things people need to move around in crisis migration, and particularly as the demand for iron changed the military and economic calculus around the region. Short answer: trade took an enormous hit overall, but certain kinds of goods were in tremendous demand, and supporting the migrations and armies that roamed the lands would have provided for the livelihoods of many.
Impact on technology, culture, politics So "regression" is a hard term here. We moderns may assume that the loss of advanced writing systems, particular modes of agriculture, and complex political systems represents a "regression." But it may not have felt that way to everyone. Technology and culture were linked in this time to an enormous extent. If you didn't like the Hittites, you probably weren't all that sad to see their material culture go. Systems of writing in particular were inevitably political, and it's in the aftermath of the collapse that we really start to see the rise and spread of the alphabetic system of which we are inheritors. Alphabets are in many ways "less advanced" than the systems they eventually replaced, but they give access to writing to a much broader group of people than a few highly trained scribes.
Political systems saw the same shift. Yes, the great and mighty empires diminished or even disappeared, but in their place flowered a huge array of new systems, in some cases quite radical experiments in governance. The one of these we know the best, the Hebrew experiment, was an attempt to graft the virtues of the nomadic system onto a settled lifestyle. Of course, this system failed... its limitations on warfare, centralization of power, and slavery made it doomed to fail in its brutal environment. But its ideals linger to this day, and we cannot imagine what the world we know would look like had they not been given the chance to flower that they were given in the aftermath of the collapse.