Hello Stan,
Riotjs is more of a framework and to be honest, to get frameworks like these to work on a Joomla environment is close to impossible. Even if it was possible, we'll take years to get it compatible with 3rd party templates and extensions.
For instance, the "Foundry" framework which is available on all of our extensions was a massive tweak over the past 4 years from all the problems we gather. Foundry was a fork of Javascript MVC. The idea and concept makes it a very good framework but it isn't practical in a world where hundreds of different modules / extensions co-exist on the same platform.
If EasyBlog was a standalone app that doesn't co-exists with other frameworks from other extensions, modules or templates, riotjs / angularjs / jmvc is definitely the way to go because it helps us write less codes while still maintaining the same set of functionality.
Also, another problem with these frameworks is their templating architecture. There will be a learning curve because the way the templates are populating these variables. No doubt, these templating architecture is the best because it can be blazing fast but to most web developers, these learning curves are not only time consuming, it costs money to learn.
Joomla is a php driven project and most of their templating architecture derives from PHP and we tend to keep it that way because automatically anyone would be familiar with our templating structure.