Not exactly unhappy but why vanilla? By using transpiler and bundler, you get to,

- Use better JS (TypeScript) to be sent as ES5 (down to IE6 supoort) without waiting for people to upgrade their browsers to the latest, which is forever.

- Upgrade to latest specified version of libraries without having have to check every site and download the min.js or change the script tag url manually and dependencies are resolved automatically.

- Get to use stuff like stylus which is already far better than CSS 3 syntax and again, no need to wait for people to upgrade their browsers.

- Bundle all JS and CSS as a single file (and place all the other assets like images at a specified location automatically), which can be cached for instant load from second page, unless your frontend code is so fat, a single file becomes too huge for it.

- If your server side is node.js, you get to use a completely same language (TypeScript) for backend and frontend.

The problem is one of culture. A reliance on complicated tooling requires specialization to these tools, which slows down team building time.

I've rescued several projects where more time was spent on making the lives of the developers "easier" than actually solving the problems of the user. Bike shedding and navel gazing is a huge problem in our industry, even if we don't like to admit it.

If you build components that use other components, without using a bundler, you constantly have to remember/know what uses what to get things to load. This may sound like not a big deal, but it doesnt take long at all and suddenly you've got loading issues!