It's a result of a strong campaign by http://uservoice.com http://uservoice.com. They've been pushing hard for the past 1-2 years and, if you were watching care

It's a result of a strong campaign by http://uservoice.com http://uservoice.com. They've been pushing hard for the past 1-2 years and, if you were watching carefully enough, you could see those buttons slowly but surely appearing on more sites. They've simply reached a tipping point now so you notice them. It's somewhat akin to seeing a specific car model more often if you own the same model -- once you notice a pattern, it's difficult to un-notice it. I like the UI. I dislike the UX, or rather what the button does to a site's overall UX.