I think we need to have as much tools as possible to achieve better privacy with bitcoin transactions.
Using something decentralized would be ideal, but most centralized exchanges already acted similar like mixers for years.
People who use centralized exchanges, don't use mixers, say they dont have anything to hide, and say they care about privacy are nothing more than hypocrites. 

All big traders are holding coins on centralized exchanges, and if you didn't notice Coinbase exchange is custodian for most Bitcoin ETF's so far 
https://blockworks.co/bitcoin-etf