Clearly the exchanges provide high visibility and liquidity and that is integral to the value of a token, since a top exchange will actually give that easy of buy and sell. That happens even with the traditional company shares and stocks, the price is very linked to what exchanges list them, for example the same share can increase up to two fold just because it is in the NASDAQ index. Of course, the exchanges are going to take as much advantage as possible from this, after all they are making a nice contribution to the value.