I think there is an element of people using things because they are new and shiny, yes. But plenty of people use React and Angular over jQuery because they make 1000x more sense when putting together a large web application with multiple developers contributing to the codebase.
Sure, for larger projects a good, well-thought out and consistent framework is a godsend. No doubt about it that plenty of people make very good use of the frameworks and libraries at our disposal.
But on the other hand I cannot count the number of times I've seen Angular included for a simple contact form with validation on a static site, React to render a single trivial dynamic list or a nice, but basic JS lib that only works in module form via NPM exports.
Sorry if I sound like a fortune cookie, but it's true - if all you've got is a hammer, everything looks like a nail.
Since 2001 or so, I can count on three fingers the number of variable collisions I have experienced in small- to medium scale projects. That I as a newbie now have to understand and manage various module systems in order to embed a lightbox on my site is a huge jump in complexity for a gain that is at best negligible in practice.
And while you and I probably have worked on some higher-complexity use cases, I think we would be kidding ourselves if we assumed that this constitutes the majority of the web.
Because that's not Facebook-scale, it's the dude around your corner selling dishwashers and reparing washing machines, trying to get his inventories's prices from an Excel sheet onto his page with a minimum of fuzz.
And the number of Aurelia users is rapidly rising not only because it's new and shiny and easier to build complex web apps, but also because it's more natural and standards-compliant than frameworks such as Angular. A natural reaction to seeing what's missing or going down the wrong path (as in the case of Angular 2).
