One disadvantage of decentralized platform is the speed of trades compared to traditional platform. It is also much higher transaction fee than the normal trading platform. Even security is also an issue like what happened in Etherdelta. I like decentralize platform but I think it needs more time before it is fully adopted.
I agree, DEX like BarterDEX are not for every crypto user, if you don't mind kyc regulations and don't mind some risk from hacks and scams from using centralised exchanges then DEX is probably a lot more trouble than it's worth in many ways, slow and requires effort to learn new way of thinking based on things like utxo and atomic swaps. Maybe 80% of small-medium traders will not bother to learn, but DEX niche will still be substantial.
I disagree though, BarterDEX fees are cheaper, and security issues are non existent, you always control your private keys, and there's no central website, so no chance of phishing or dns spoofing.