Comment by lxgr
Same here. I find it useful, and it doesn't feel like it took several engineering years to build, diluting Mozilla's focus from "just building a browser".
Actually, whenever I hear people argue that that's all Mozilla should ever be doing, I wonder if they really mean a HTML and Javascript engine? While that's important, browsers are more than that; the chrome matters too.
I think a lot of folks feel that Firefox has outstanding features and issues that prevent more widespread adoption and current user happiness, as opposed to spending effort on AI features.
The average person doesn't care about an AI pane and that won't cause them to change browsers. Mozilla adding tab group support actively got non-tech people I know to switch, in addition to uBlock Origin and generally better privacy.