Well. I hear you. But, is it really centralization if we are adding one more ‘super node’ as we seem to be doing in this case?
I am all for even more big companies having even bigger networks. As long as they cannot stop new players from emerging and getting bigger, these centralization vs distributed trade offs are largely academic.
IMHO, it comes down to the economic structure of peering in the US (as I understand it? And not sure globally?).
Tl;dr: You have negotiating power based on the number of end clients you connect to the network.
And connectivity is an extremely high capital, low margin, and predatory industry.
Consequently, "build useful services, that cause more people to connect through you, that then allows you to favorably peer and lower your costs" is Cloudflare's strategic business model.
So yes, they would very much like the entire Internet to run through them. Or more accurately, terminate to their customers.