Some? All decentralized exchanges don't ask for personal information. If they do, then it's not a decentralized exchange, but a centralized exchange. The whole purpose of these exchanges is to not deal with central entities anymore.

I do however agree on the liquidity being a major hindrance in terms of being more adopted. This is where tokens on Ethereum are doing well. It's super easy to switch from token to token since everything runs on the same platform.