I think a big contribution to the rate of change of JS is that there is not yet a division between frameworks that do display stuff and frameworks that do utility/heavy lifting - this is partially due to the fact (IMO) that a lot of systems isolate heavy/complicated logic (especially business specific stuff) to a backend which JS queries to source data to operate over.
All of the current frameworks are intimately tied into display logic and that display logic is constantly in flux with shifting trends, device/accessibility support and shifting coupled technologies (css-flex, css-grid...). This lack of an isolation is causing people to jump frameworks to capture support for newer design trends and the like but... I think it's getting better. I'm not a front-end dev but react is the first offering I've seen that seems to really strongly reinforce a decoupling point between display and logic.
Really though, look at the realm of application development, in that realm users are accepting of crazy out-of-date UIs so the sterotypical "Oh this was definitely built with Java" (with substitutions for MFC and Qt) is sort of accepted. So, I may be off base.
All I know for certain is that there was a period in the 00s when I was really hopeful that all website design would be handled seamlessly by my designer coming in and throwing some style-sheets on everything and no changes to markup would be required - that time has passed and the responsive web is baking in a really strong assumption of native-application-like functionality, this isn't bad or good - it just is.
So, in summary, I'm still hoping that the majority of front-end work can shove a crowbar between the declaration of logic and the rendering, but I feel like the rate of UI change and shifting display thingies will forever outpace attempts to provide a unified toolset that actually captures the majority of intended uses.