I'd add two important aspects to your arguments:
A decentralized exchange renders front running inefficient. Imagine the advantage Poloniex owners have over other market participants: only they can see every move of every whale and every big deposit made by them.
A decentralized exchange allows several smaller exchanges to combine their order books and help each other with liquidity.
Excellent points!
ohh, if only I could vote more than once to this comment lol
No problem I'll do it for you