It is the general consensus that competition in the market place is good for consumers and propels business to find creative solutions that create value in the econony. I would say that isnt always the case, Rockefeller had something like 90% market share before litigation of antitrust began, by the time the case was adjucated their market share had already slipped; what this indicates is that even when one party holds 90% of market share (and probably total wealth for that matter), the market will eventually cut them down to size. At the same time, rockefeller was responsible for bringing a groundbreaking innovation to society. So, it was good that initially all that capital flowed to him, because he was using it to move society forward (at least in this regard), and it was also good to see that capital flow away on its own, because it was needed elsewhere.

I would also point out that the centralization of companies into todays megacorps is influenced by many factors, economies of scale may be one, but so are intellectual property laws (we really dont need them!). In fact, I would venture a guess that most regulation is written by the companies that are being regulated, that keeps competition at bay, and they wont regulate themselves downwards in the food chain. Finally, I would say the centralization really took place during WWI/WW2, it was convenient for the government to shout orders at a whole 3 people to build tanks instead of automobiles; this centralization is a strategic goal of the united states government, and enacting it through secret deals (rather than law) is a preferable method to preserve state secrecy.