The IANA controls IP address allocation, so in that way, IP is centralized. And yes, as you mentioned, DNS is also centralized, and so is SSL/TLS. Having multiple options doesn't make something decentralized, it just means there are multiple centers.

And while I don't like how much control centralized organizations and corporations have over the supposedly decentralized Internet, we certainly shouldn't throw it out until we have something ready to replace it, and even then, it would have to be a gradual shift.