I can agree with you on the fact that ICOs have been the first actual "killer application" for Ethereum. But they only work because they're based on another lie.
People buy into these ICOs because they get tokens that they assume to increase in value. It's basically a "get rich quick" scheme. It worked an astounding number of times, and once people caught up on that, the value of Ether started to skyrocket as everyone and their grandmothers wanted to have a piece of the cake.
Why did the tokens increase in value? Because enough people believed in the "visions" of the startups behind the ICOs, which usually weave some story about future utility of the specific token into their business case precisely to make people think that these tokens will one day be more than just a speculation object. Once enough people believed that, the tokens became extremely good speculation objects, as they were growing in value, and that made people get rich quick, which made Ether skyrocket, which made more people get rich quick. See last paragraph. But the important takeaway is: you need that perceived utility value to kickstart this entire sequence of events!
Okay, so why are the tokens supposed to have any utility value besides being speculation objects? Because the startups have business models centered around Ethereum and smart contracts and of course utilizing their token that they intend to grow into a real business. If you now assume - just as you yourself have stipulated - that smart contracts on Ethereum are used for nothing other than the facilitation of crowdfunding coin offerings, this means that any other business model is assumed to fail. This in turn means that all those tokens have no utility value whatsoever. This in turn means that they eventually lose their speculative value, which is based on people believing in them one day having utility value. It will probably take a while, since beliefs can be strong and masses of people tend to be dumb, but eventually it will happen. This in turn means that crowdsourcing yet another useless and worthless token won't work, since why should anybody invest anything into it? And this finally ruins the nice killer application of crowdfunding via ICOs.
