Hey Yuri, IMHO, this section is the closest thing (thus far) to an 'elevator pitch' for the direction of the movement:

https://meta.wikimedia.org/wiki/Strategy/Wikimedia_movement/2017/Direction#O...

You could probably even knock it down to "The Wikimedia movement serves open knowledge to the world across interfaces and communities. We break down the social, political, and technical barriers preventing people from accessing and contributing to free knowledge."

Anything that short is sure to lose the nuance in the longer document (which I'm sure we've all read!), but it might be a little closer to what you're looking for. Adapt as necessary.

Yours, Chris K.