Many ICOs have their token sold at a fixed price vs. the ETH. For example: 1 ETH = 1000 Tokens.
So does it really matter if the prices of ETH/BTC is dropping?
If anything, then buying now you get more Tokens for the $, right?
Well, maybe for the long term it will be more profitable. But I think when Ethereum is cheaper, not many communities participate in ICO, and this makes the prospect in the short term very difficult, while some people choose ICO to get instant fluctuations.