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.
Because there are so many tokens on commercial decentralized sites, so the transaction volume is very large, leading to transaction delays and high transaction costs. If the commercial pages overcome these two things, the success rate is huge.