When you operate at the DNS level, you get to do all kinds of cool things with site traffic. Cloudflare started with a value proposition based on security, but low-cost hardware and advent of cloud technologies have allowed them to easily expand their offering to CDN and apps.

They are freemium because they need to collect as much traffic data as possible to learn to identify threats. Same reasoning as Akismet spam filtering started out with. They also have enterprise level plans, which probably drive more revenue.

Plus, they are only 7 months old. Kinda early to be hatin', no?