I'm not sure why you need CloudFlare when the profit from advertising is more than enough to rent entire serve racks. Is BitcoinTalk's revenue being siphoned off?
That would also not surprise me.
It's to prevent DDoS attack.
That's part of the reason but I don't know if there's much more CF can get since they've managed to spend a lot of money on making things that'd need Javascript to work to no longer require them (such as recaptcha iirc). At the same time, if they can get other tools to run without Javascript what's to say they can't do that with most other tracking tools they might be using (particularly for anti ddos/legitimate user fingerprinting at least).