I am using decentralized exchanges for trading as they list coins I cannot find elsewhere. They are hacked sometimes, not user
friendly, having low volume and very bad support. Centralize exchanges are more safe ( the good ones offering refunding if hack happens ) .
Binance is opening a decentralized exchange as well, hardly waiting to see how it will look like.
Decentralization is better, because all transactions are more open, meaning they can be monitored because the server is not centralized. If centralization can occur data manipulation or prices that are very detrimental to the users. Therefore, many countries, especially developing countries, still apply centralization in everything, including trade.