Precisely. Keep proprietary software out of Linux. The main reason we can get people to switch to Linux is freedom. If it becomes as full of closed programs as Windows, we won't get anyone to switch because there's no reason to (and no benefit). It's FOSS or nothing.
I love linux. It's my operating system of choice. I think, all other things being equal, it's a superior operating system for just about any use case (other than really edge-case scenarios). I especially enjoy the freedom of the operating system, in every sense of the word as applied to software.
But understand this: the vast majority of the population just doesn't care about "freedom" when it comes to software. They care more about two other things, about in equal measure: 1) does it work well enough to do what I want; 2) can I hold somebody else accountable if/when it doesn't? The latter may be even more important at the "big enterprise" level, where generally "I need to make sure my ass is covered if something this thing touches breaks" outranks "I need to make sure this is a good solution for my company" on the list of priorities. The fact is that FOSS does a decent job of filling (1), but a really poor job of filling (2).
In light of this, the notion that people will switch to linux simply because of the free-ness is a bit, well, naive. Sure, it happens. It isn't happening in large numbers and, in my opinion, isn't likely to.
Why wouldn't they just run those same FOSS programs on Windows or OS X instead? It's not like Linux has a monopoly on running open source apps. In general, people use computers in order to use computers, not to make a political statement about how much they disapprove of ways in which everybody else uses computers.
If FOSS OSes have poor to non existent support for proprietary software, there is no way they will be able to compete with proprietary OSes like OSX and Windows that fully support running FOSS applications.
The ability to develop or run proprietary software, if I so choose, is a form of freedom.
