I really think these IEO thing is only good for the top exchanges and these is because they have the liquidity and the traders to pump a coin after listing, which is why their IEO projects are usually successful.
But the smaller exchange don't have the same and their IEO success rate is no way near the top exchanges. Maybe 2 out of 10 IEOs conducted on the small exchanges would succeed, while top exchanges boast of a success rate of like 9 out of 10.
They are businessman they can do what they think it's good for there business. The real question is that method proper for everyone or not..? I can agree with your words big exchange are doing good than small exchange. And this success tricks or game i don't know that but i know some good quality project are coming because of them. Investor also show there interest now. So if we have to forward with positive side if there is negative side of IEO then we have to stand for that also.