But many dev teams start their ICO without a bounty. The bounty launches several weeks or months later just to make the project more popular. Remember that the bounty requires some investments from devs too.
Of course, bounty campaign requires periodical time investments on dev's part, but I've seen how much attention such campaign could bring. Human resources are much more valuable than time, don't forget that!
I agree, but devs should check everything before the start. Still, bounty is profitable for everyone if it is well organized.