Because of the low barrier to entry and the large amounts of available capital, there is strong financial pressure on companies to do an ICO if at all possible. The ability to raise substantial capital without issuing equity, and without well-defined legal obligations, is an opportunity that's seen as too good to pass up.
In many cases, projects don't truly need a blockchain or a token. In fact, unless the features of blockchain are absolutely vital to a project, it is cheaper and easier to go forward without it. To require a blockchain, a project will need to make quality use of blockchain-enabled features: decentralized governance, immutability, true digital scarcity, and so on. Similarly, projects that release tokens on public blockchains must sacrifice privacy and speed. It is imperative that anyone evaluating blockchain projects keeps these issues in mind.