Hey now, they're "actively working to develop a solution that will enable Hangouts to work in Firefox without a [NPAPI] plugin" [0].
These things take time, you know. Especially with the limited resources of Google, Mozilla not already having announced the deprecation of NPAPI plugins two years ago [1] and there not already being a web standard, mainly pushed by Google, that enables video and audio calling for every modern browser out there [2].
It's hard to understand who you're trying to blame here, but it sounds like a classic case of the "two ways of doing a thing" (the deprecated way and the one that doesn't work yet).
