A real Manifesto is still to be written. Till then, Michael's response on one of the repository issues gives a great summary:
"... I started this project as an ultimate starter project for Raspberry Pi enthusiasts. As a matter of fact, for most of the contributors, the MagicMirror project is the first open source project they ever contributed to. This is one of the reasons why the MagicMirror project is featured in several RasPi magazines.
The project has a lot of opportunities for improvement. We could use a powerful framework like Vue to ramp up the development speed. We could use SASS for better/easier css implementations. We could make it an NPM installable package. And as you say, we could bundle it up. The big downside of of of these changes is that it over complicates things: a user no longer will be able to open just one file and make a small modification and see how it works out.
Of course, a bundled version can be complimentary to the regular un-bundled version. And I'm sure a lot of (new) users will opt for the bundled version. But this means those users won't be motivated to take a peek under the hood. They will just remain 'users'. They won't become contributors, and worse: they won't be motivated to take their first steps in software development.
And to be honest: motivating curious users to step out of their comfort zone and take those first steps is what drives me in this project. Therefore my ultimate goal is this project is to keep it as accessible as possible."
~ Michael Teeuw