Yes, I agree.
I was thinking from point of view of ICO owners, if would that be so difficult to add a payment gateway along with ETH. I guess not. In-spite of, it can reach to more people and have more token sale, they are not implementing, so I am trying to figure out if there is any other reason.
It is really easier for the issuers to calculate their needs, spending and requirements in USD rather than crypto as the price of cryptocurrency is very volatile. Most of the ICO also do convert the received coins to USD at current price and give the token in price relative to USD value.