[1] https://bugzilla.mozilla.org/show_bug.cgi?id=856375
People propose plenty of things with technically sound code, but there's far more to developing a platform than including everything that's technically sound. You have to make decisions as to what you wish to include. Once a something becomes near universal (in terms of marketshare, not in terms number of browsers; see IE's peak for the clear examples there!) it becomes treated as a baseline; once it's there it's incredibly hard to remove. Every time something else gets added that's more code to maintain, more code to ensure correctness (and security!) thereof, and a higher barrier of entry to the browser market. As a result, the default answer to adding anything should be "no".
Many things of interest developers might want to do currently require co-operation from the browser vendors, and their default position is 'no' unless it is in their commercial interest. Also, any one of the browser vendor vetoing the proposal is enough to kill it. Apple/Google/Microsoft are all huge companies with many products, so it's quite likely that you are a direct competitor to at least one product from one of the browser vendors, giving them extra incentive to veto most of the time.
Until the web is a platform where the vendors don't have the power to veto basic functionality like decoding an image it will remain the plaything of the browser vendors, used to bludgeon their competition.
Also our empiric measurments have shown, that WebP degrades more gracefully as you lower quality (compression artifacts aren't as visible) which allowed us to save about 30% of bandwith total by serving WebP to Androids and Chrome clients.
Reminds me of MNG, where we had an animation format with support for alpha and either PNG or JPEG style compression of frames, but it never got a pervasive browser implementation so it died. (I get the impression there were strong technical reasons for that, of course.)
Coincidentally, MNG also indirectly solved this problem. JNG was a subset-format of MNG that provided JPEG-compressed static images with optional support for alpha, so implementing MNG implied implementing JNG. But we never got it on the web.
At the very least, instead of just saying 'WebP is bad', they're putting their money where their mouth is and advancing the state-of-the-art in JPEG encoding so that people won't need WebP (other than the alpha channel use case, that is.)
Are there many websites using WebP that aren't Google properties?
I'll be interested to see if a VP9- or Daala-based version of WebP is more compelling.
Try gif2webp and gif2apng converters on this example, and you will know:
https://www.google.com/logos/doodles/2014/world-cup-2014-54-...