I think your understanding of the history of computing is flawed.
As somebody who lived through the events you mentioned as an adult working in industry, I can assure you that the sentiment you believe was felt was actually not felt.
Mouse wheels were seen as a very good thing when they first came on the scene. They gave the power of the three-buttoned mouse, but also made scrolling much simpler.
The same goes for tabbed browsing. It was one of the best features of Opera for a long time. Everyone I showed it to at the time thought it was very useful. And it was one of the best features of Firefox, too, when it was still Phoenix.
And the same goes for fonts, and CSS (although to a lesser extent). Their benefits were obvious from the beginning, and I don't remember them facing really any resistance.
Contrary to popular belief today, JavaScript was not seen as good when it was first released, and it should not be considered good today. In the mid-1990s it was generally seen as a rather bad and limited language. That's why it didn't see much use until the mid-2000s. The first generation of developers who experienced it found it inferior to existing technologies and generally refused to use it. Even today, it's still a very flawed language (the problems with it are well know; I'm not going to regurgitate them here).
The problem with Firefox lately isn't that there has been chance. Of course change can be good. In the case of Firefox, though, the change has been utterly horrible, and caused far more problems than it brings in benefits, for a huge number of people. This is reflected very well in Firefox's ever-dropping market share.