effectively, patents protect the two constituent groups required for innovation: (1) creators and (2) investors.
music, art, film, restaurants, and mobile apps demonstrate that patents are not necessary for people to invent (though some IP like copyright seems mandatory). in some fields, the joy of creation and the promise of financial gain, even if unprotected and unsustainable, is sufficient motivation for invention.
the common thread, of course, is capital efficiency. it's far easier to risk investment and innovation when little money is required. investors are needed for innovation in capital intensive areas, but investors historically have been ROI motivated and sought assurances, such as patents, that their money will yield a return.
crowdfunding enables creators to break from ROI-investors and find financing from a different set of people: those who want not a ROI, but a specific product or service. most importantly, these "investors" care less about patents or the long-term viability of a company. they just want a product/service to exist -- from anyone.
we're already seeing this unfold on kickstarter and indiegogo. the question is whether lobbyists and governments cripple crowdfunding, or allow it to reach its maximum potential.
if people will innovate, regardless of patents, and other people will underwrite products, regardless of patents, why do we need patents to foster innovation?