I disagree. In my opinion the United States (to take one example) is more mediocre now than it was 200 years ago. The larger and more centralized the government, the slower and more unresponsive that government becomes.
I also disagree about the "committee" statement. If anything, centralized governments are more dominated by committees than decentralized governments. This goes for any organization, not just governments. A small business or small chain of businesses is less likely to be dominated by committees than a multinational corporation.
I agree with your assessment about the US now versus 200 years ago. I disagree with your reasoning as to why. 200 years ago, it was a Republic, with power concentrated in the hands of a "franchised" voting class who either owned land or served time in the military, and was removed from the "general public". Now it's a Democracy, with policy being set by the opinions of just about anyone and everyone. It may be larger now, but it's less centralized, and increasingly oriented toward providing the most "freebies" before the next election, instead of focusing on the long-term needs of the country.
There are a few "gray issues" to "centralization"; a political or economic entity with more size may more likely to be run by committees, but the power in that larger entity is likely to be concentrated in one or two such committees, which make up a disproportionately smaller fraction of the whole body. In the TES world, the destruction of the Amulet at the end of the Oblivion Crisis leaves the Empire in the hands of a committee. It remains to be seen how Bethesda handles the "history" of that time, and the ensuing maneuvering for power by claimants to the throne.
I really don't want to go too much farther with this, or risk turning it into a headed discussion on politics, which is ALWAYS a bad idea in an open discussion group.