If you conduct IEO, then it should be a popular exchange with a large trading volume, but usually you have to pay a lot for IEO ... Therefore, I think that it is necessary to attract traders with some unusual conditions!
I agree that for good exchange for IEO it is necessary to have a good some of money, but IEO is conducted to collect money for development of startup. If startup would have money it would not conduct IEO.
Well, it can be called a kind of paradox. Of course, there are projects that manage to conduct IEO for free, they pay part of their coins to the exchange. But as a rule, there is no trading volume on such exchanges.