While I'm certainly not opposed to this kind of expansion, it's worth remember that Viking Conquest was originally made as a mod, and not an expansion. This kind of thing will be created by modders, not the company, though they may choose to formalize it as they did VC.
Which is not a bad thing. Taleworlds needs to focus on finishing this game and expand upon existing systems before launching new big ass projects.
On a purely academic note and for the sake of interest in the subject matter:
You have reason to doubt the existence of bandits, anywhere in the world at any point in history?
Name me a time and place, any, on earth, where bandits weren't a legit threat.
While you're right on the surface, how do you define a bandit? An outlaw? Ie, someone who is outside of established law? That could just be someone living outside of the constraints of society. Someone who uses violence to take other people's possessions? How does one differentiate between a raider from tribe X, and a bandit? Or maybe escaped slaves? Therefore forced to live in hiding on the outskirts of society?
My point is that Roman society tended to name anyone who didn't fit in their political hierarchy as a bandit. If the members of an annexed tribe refused their defeat and continued fighting, they would be branded as bandits by the Romans, even though they would technically be closer to a proto-independence/nationalist movement.
In fact, even the source posted above specifies that:
"Some rebels might be classified as bandits so as to be more easily dismissed. Tacfarinas was a deserter from the Roman auxiliaries, who belonged to a nomadic Berber tribe from what is now modern Algeria. This tribe had rebelled in 5/6 CE, and then rebelled a second time in 17 CE under Tacfarinas, who managed to almost wipe out part of a Roman legion in 18 CE."
In modern terms, bandit means someone who violates the constraints of the law for financial gain. To the Romans, it applied to political dissidents and revolutionaries as much as it did to criminals.
It was essentially a form of state propaganda. In the same manner that in the modern day we refer to independence movements we approve of as "Freedom Fighters" and "Revolutionaries" but those we don't like, are "Terrorists" and "Criminals".
The escaped slaves who revolted during the three serville wars, were branded as bandits by the Romans, even though they are more comparable to an international freedom fighter movement. In the case of Spartacus' revolt, there were even alliances with Cilician pirates, Gallic tribes, and even plans for an alliance with some Roman officials such as Quintus Sertorius who was in Spain at the time and had essentially seceded from the Republic. Now that's some high level banditry, right there...
I'm pretty sure Jesus was branded as a bandit and was essentially executed for causing trouble amongst the more independence-minded Jews.
Roman legionaries and auxiliaries who had served under a defeated general during the many civil wars of the empire, would usually be given the opportunity to join the victor's banners, but would just as frequently end up being outcasts and therefore, branded as bandits.
Even goat herders generally had a reputation of being semi-bandits due to their lifestyle. And were as a result, prized recruits for skirmishing units amongst all nations of the time.
My point is that 'bandit' doesn't mean the same thing now as it did then. As a matter of fact, bandits of all stripes were disparagingly referred to as 'latrones' which I'm sure you'll notice, is amusingly close to 'latrinea.' Which is admitedly a linguistic coincidence, but does give a good indication of how bandits were perceived at the time.
But yes, you're right about the fact that Rome itself was a bandit-infested nest. As are all urban centers with high population density. So nothing new there...
The 'law' being seen as something inalienable from an individual, is a concept that only rose to prominence with the advent of nationalist movements during the 1800s. Meaning, in many nations today, you can't strip someone's rights before the law - which is not to say that it doesn't happen, but it is considered against the 'rules' and an abuse of power. Before that, in all countries, throughout time, the 'law' was as much a shield, as it was a sword of Damocles. If you were a team player, you would be afforded the protection of the law. If you rocked the boat, all rights and privileges could easily be stripped from you. In which case, you were pretty much ****ed.
While the Roman Empire gives us the impression of "a better age of a more civilized time", it really was not. Sure, when it comes to art that is the case, and when it comes to the army as well. Soldiers were in equal measure builders to the point where these jobs were undistinguishable. Build a camp from Mount&Blade? How about build a fort.
But the social element was pretty much the same as in Medieval Europe. Rome had more civil wars than pretty much any state I read about, and I read about a lot.
Arguably, there is no Roman Empire. It doesn't exist. There are Roman EmpireS. Plural. The early imperial period has nothing in common with the late imperial period, and it's practically a different country - in the words of historian L.P. Hartley, "The past is a foreign country; they do things differently there." That is as true for us compared to Romans, as it is to a late period Roman when compared to an early period Roman citizen.
The time periods mentioned in the source you posted, are for the most part dated within the vicinity of 100 AD. Which is a particular time period of the empire.
The social element was, as you say, indeed pretty much the same as in Medieval Europe, but only after the crisis of the third century, during which... I believe it was Emperor Diocletian, but I could be wrong... essentially established the foundations of the feudal system by binding local populations to their regional governor. It was the hybridization of that particular iteration of the Roman societal system, along with the social structures of Germanic migrants, particularly the Franks, that resulted in the feudal system of the medieval period.
Prior to that, the claim of a "better age of a more civilized time" was arguably true in terms of technological advancements and scientific progress. The problem is that for a number of reasons, the Romans were - like the Greeks - utterly incapable of applying their knowledge to practical pursuits. They had technically discovered (or rather stole from the Greeks) steam engines, railways, proto-computers, theorized the existence of the atom, et cetera... but did nothing with those inventions and discoveries.
It was only shortly prior to, during, and after the crisis of the third century, that everything went tits up.
Not that any of this matters anyway, since should a mod/dlc be made for this time period, most of the historical accuracy will have to be tossed out the window for the sake of game mechanics and playability. Like I said, I only bring this up purely out of interest in the subject matter.