They are. Most companies using BSD-licensed software realize that it just makes sense to not release contributions back to the community. Having to backport whenever a new release comes out just to hide a couple shiny features quickly becomes very much not worth it. Netflix in particular is a major contributor in code, cash, and community, so saying the mods aren't free software is utter ignorance. The meme that only restrictively-licensed free software gets people to contribute back has frankly been debunked from here to mars and back.
... except that they are. Scott Long and Adrian Chadd are working full-time for Netflix, and other developers (e.g., Kirk McKusick, Gleb Smirnoff) have been hired from time to time for other work. Aside from short time periods while Netflix is testing kernel patches (on live traffic!) all their FreeBSD code is in the SVN repository.
If the company is willing to contribute it back, it is probably good software and the company will probably be a good partner. If the only reason the contribute the code back is because of the license, I would imagine they will suck as a partner and the code probably won't be of good quality.
I look at BSD / MIT as foundational licenses that anyone can use. Those companies that don't understand the business case for getting their changes put back into the mainline of a project just aren't worth your time. It is a nice self selection process by companies and a good indicator if they will get the whole open source thing. Its like a spam filter for source code.
For example, Netflix is contributing source and money back.
