> They really need to get out of this stale and boring state and innovate more
I'm just as excited as you are for side tabs, but I don't think browsers need to be constantly innovating their UI. In fact, the last time Firefox did that it took a week of tinkering to get it back to a usable state, and I now have the constant "Compact (Unsupported)" layout hovering over me, reminding me that one day I'll probably have to tinker even more.
I use the browser for at least 8 hours a day, I don't need the experience constantly changing, it's a tool. "stale" and "boring" is also "stable" and "dependable".