There are capabilities to use the existing DNS system (or an EthDNS system in the works) for human readable names with IPFS, but you can also use other channels like pubsub to resolve mutable content like IPNS names quickly - so IPFS doesn't actually require DNS at all. Multiwriter IPNS records are also a work in progress, though I disagree with your characterization that somehow only allowing one key to edit a particular signed record somehow makes the network itself centralized...