It depends on the ICO, sometimes they need is the waves address instead of eth address. But most of the ICO now choose the eth because of contract. You can join in ICO but to can't receive your payment and it is unfair for you, only need to do is to follow their needs. And if you think that it is hard to make an etherium address it is NO, just go on myetherwallet.com and choose what key you want to use. And the eth address is there.