I think most of this discussion about openness is not taken from the right angle.

Basing your platform in mainstream Linux and open source components makes a whole difference for platform development.

It actually has also important implications for application development (generic programming language, wide public APIs) , although a closed but popular platform with a rich API can get you to a similar level of benefits.

It has little implications for end users, except for those really interested in platform tinkering and applications with a Linux or software freedom agenda.

No more, no less.