One possible reason to push for improvements before accepting the new format into Firefox is suggested by Justin Lebar in a comment on http://bugzil.la/600919 h

One possible reason to push for improvements before accepting the new format into Firefox is suggested by Justin Lebar in a comment on http://bugzil.la/600919 http://bugzil.la/600919: "In general, Mozilla should use its weight to improve the web in the long term, even if doing so is unpopular in the short term. In this case, by not accepting WebP in its current form, we're putting pressure on its developers to improve it in the ways that we think are important. Once we accept the codec, we lose this leverage. [...] Remember that even if we landed this patch tomorrow, it would still likely be years before this format saw wide adoption. The argument is that it's better to wait and throw our weight behind something we think moves the web forward, if and when that arrives."