Mainly because it is on hype right now. It is just another way of funding your own project. Just like Kickstarter, Gofundme and the likes. However, you do not have to offer anything for getting funds. If people like you idea, whitepaper, if they believe in you - they decide to invest (give you money). In return you give tokens (basically air) in hopes that when you deliver users will be able to cash out those coins (use them somewhere).
Recently there were some news about several ICOs which said they will offer equity (namely, some NYC hotel and Lympo). We will have to wait and see how it turns out in the end.