Sometimes I feel some projects are all about branding, the majority of the ICO projects are about sales and marketing.
I personally market several projects: the retention rate for ICO with a decent project is much higher than the the mediocre one. I think fundamentally ICO fail because of the product fails to meet its promises.
I think one of the main reason ICO's fail is because of the team behind the project and marketing because the product will be deliver after the ICO so they need to attract investors to put money on their project, also partners and advisors helps the ICO to be trustworthy.