How long do you think something like that should take? It's already been 25 years... I think it says something about the browser ecosystem and the language itself.
The entire WPF ecosystem for example was developed and refined in a fraction of this period. Heck even .NET itself is only 14 years old.
I don't think that's really a fair comparison. I would argue that you should start counting from the adoption of UMD modules and npm for package management, since a universal package format and dependency management are requisite for an ecosystem to get of the ground.
Languages with one single corporate implementor obviously will centralize and standardize their library. Languages with a bunch of competing implementors stay fragmented. JavaScript is a lot like C++ in this regard.
Javascript development as you see it today started budding with Mootools, Prototype, jQuery, YUI, etc. Wasn't until the early 2000s that the concept of unobtrusive javascript was even a thing. Then bundling assets came, asset pipeline concept from the rails world got popular in javascript land, then you had all the grunt, gulps, webpacks come into the picture -- Point being .NET came out in what, 01? So Javascript has a few more years, I think we will be in a good place in a couple of years. Besides that point, how much work behind the scenes before .NET was even ever released to us was going on? How many man hours of development was put before that first public release? My guess is a lot more than we think.
The entire WPF ecosystem for example was developed and refined in a fraction of this period. Heck even .NET itself is only 14 years old.