I think the important thing about the language being free is that it is key enabling feature of the list you just gave. If the Wolfram Language truly was free then Wolfram Research should be able to publish and distribute a language specification and it should be possible for a competing group like, say the team that made Octave, to create a competing platform for the Wolfram Alpha language. Besides a few bells and whistles in the IDE, a piece of source code written in the Wolfram Language should be portable to any platform that implements the language specification. At least, that is what I would like.

I think the reason this isn't done is because Wolfram Research would have to really take responsibility for calling this thing a programming language. They'd have to publish their sources or at least the requirements for what qualifies as a valid source. They'd also have to publish their curating methods so that anyone with access to their sources and the language specification could produce identical results to identical source code. Basically, their position would be no more privileged than Microsoft's with respect to CSharp and the .NET framework. I don't think Wolfram Research wants to face a Mono-like competitor for their language and that is why portraying the language as some general purpose tool for everyone rings hollow.