Well, the feudal commons were neither complicated nor decentralized. Feudalism itself developed from the land system at the frontier of the Roman Empire. When the Roman Empire collapsed, it was somewhat decentralized but still controlled through centralized authorities. Feudalism was governed with a system of aristocracy and monarchy, based on official agreements of rights and laws such as the Magna Carta and Charter of the Forest.
AFAIK that isn’t quite correct. While I don’t have time to dig up full references, I did find a source with a different viewpoint on this (Land Use and Society, Revised Edition: Geography, Law, and Public Policy by Rutherford H. Platt):
This matches my own understanding (from much wider study) of feudal conditions prior to the Great Plague(s), but (IMO) manages to give some unfortunate impressions:
The open field systems were generally not “commons” in the real sense of the term (although propaganda dating to the Enclosure Movements has left that impression). Ownership of strips within fields was completely private, although it was much more limited in “rights” than modern ownership.
Farmers were (in general, rules varied from village to village) expected to plant the same crops as everybody else in the fields, at the same times, and follow the same general practices, especially regarding weed control. At certain times, a field would become “common” grazing land for sheep (and perhaps geese), whose grazing patterns would tend to pull up the roots of harvested crops, helping to clear the land for the next crop.
The real “commons” were “shared but rationed and regulated access rights and obligations over resources such as pastures, forests, wastes and marshes” as discussed in some detail in a paper by Daniel R. Curtis that provides a perspective on the position of Ostrom and those in her camp:
While details varied widely between villages, and even more so among different regions, the “commons” were almost never simply open to everybody. Although I see little mention of it in this paper, it has been widely theorized that by the end of the Great Plague(s) the older system of tight access control at the village level had widely broken down because there was enough for everybody (who survived).
It was as the population recovered, and pressures mounted between the reestablishment of traditional access control and the newer, more productive, and more capital-intensive pastoral farming that the “control[…] through centralized authorities” (see top) replaced the older, decentralized system.
There is considerable evidence from primary sources for this position, widely referenced in both older and more recent research.
It’s actually very unfortunate that the original misunderstanding of the “Tragedy of the Commons” should become mixed with ideological conflicts over Marxism and “primitive communism” (which it certainly was not).
“Commons” involved a system of ownership that was different from the more modern, post-Enclosure, system of property ownership. But in its most successful form, property rights were as precisely defined as they are today, just differently.
Curtis makes the point that:
[… E]ven within those societies that managed to retain large parts of their commons over the long term, they were not necessarily more equitable than in societies without commons. Indeed, as argued recently by Jose Miguel Lana, the commons tended to be based on notions of ‘equilibrium’ (social and ecological), not ‘equity’ (in an economic sense) (Lana 2008). The commons had no real powers of egalitarian redistribution in themselves: their mere presence could not make societies more equitable — only sometimes in an indirect way, as noted in the above paragraph, by proving to be an obstacle for absentee land consolidation.
It’s my view (probably discussed somewhere in the literature but I’ve never found it) that the real driving force behind the Enclosure Movement (and similar on the Continent) was the introduction of new crops from the New World, especially corn/maize and potatoes.
These put a much higher premium on agricultural innovation. In most marginal farming communities, innovation tends to be unpopular due to its very low success rate: the vast majority of changes to established processes were probably going to fail, often catastrophically.
But new crops, and the application of new analytic techniques to agriculture that they drove, completely shifted the balance. Between them, these two factors offered much higher profits for innovation, at the cost, however, of requiring fields to be individually fenced, with clearance grazing being at the discretion of each farmer.
That’s my opinion, but as mentioned I’m not aware that such an idea has any widespread credence.
But the bottom line, whatever the reasons driving Enclosure, the pre-Plague open field and commons systems were in no way either primitive, or communism. They were complex, usually well (enough) suited to conditions, and operated in a decentralized fashion at a very local level.
 The paper is paywalled, but depending on your approach to things, you could use Sci-Hub to read it. (The DOI is in the abstract page linked to.)