While counterparty (XCP) isn't as rich as Ethererum, I wonder: is it adequate for what many of these ICOs are intended? It's unfortunate that it likely requires higher transaction fees but it seems much simpler to me (and trustless).
So I don't think there's any disadvantage in using Ethereum for token sales, and plenty of advantages like experimenting with new token sale smart contracts (different auction mechanisms to allow better price discovery), not to mention the larger suite of compatible applications (anything ERC-20 compliant like Etherdelta or 0x for decentralized exchange).
Also, Counterparty uses a port of the Ethereum Virtual Machine, so any innovative uses of it will have the same risks as using Ethereum.