More competitor, improve quality 
Agree with you, if we have just few exchanges, those exchange might be put fee transaction very high. Just because they almost monopoly on the exchange market
If the majority of crypto market appearances are decentralized markets, quality will decrease sharply, there will be many problems with insufficient volume in conducting trade and ecosystems will be damaged because various markets will compete to attract investors somehow.
But the opposite will happen if they are able to develop the central market to various countries legally, this will make the volume circulation more attractive and of course there is no monopoly.