This is one of several reasons why the GPL is a great license for FLOSS. You can GPL-license your software and contribute to the community, while offering alternative commercial licenses to companies that want them.
If you use a totally-permissive BSD-style license, you're stuck trying to charge for a support contract or custom plugins or something.
I sold my software dual-licensed GPL, and a deal-breaker for me was how long it took companies to actually purchase. They had the software, used it, and so didn't have a compelling need to buy, right now.
Though they all did actually buy in the end, and there was enough income to live on, I found the uncertainty very distracting and not worth it.
What's stopping other companies from using your GPL software in their proprietary stuff without telling anyone? Not every company out there is a startup who needs to be sparkling clean to pass due diligence for the next round, acquisition or IPO. A lot of companies out there are perfectly fine with a little bit of cheating here and there — I would actually say that most of them are. Especially when you remember about the world outside of US.
It gives you a future market share via so many people using your software for free. They won't pay if it weren't free anyway, but would use a competing piece of software. That is, without the free (as in freedom) version, few would even consider paying for a commercial license.
Did you ever think why Microsoft is so lazy about enforcing the end-user Windows licenses on non-business customers? Maybe they want kids get used to to running Windows at home, and expect it in a work environment, and value this higher than the lost revenue from "pirates"?
Note how many people still happily run Win 7, and before that happily ran XP, and before that happily ran win2k — while being very reluctant to upgrade.
It's corporations that need upgrades and support. With corporations, I'm sure, MS is not lax and enforces the licensing policy.
Which is all fine and good when you have VC funding and can run at a loss for years, or are growing at a rate where you don't care about a few cheats using your product. But, for all those bootstrapped business' your argument falls flat.
~20 years ago Oracle handed out a stripped-down "personal edition" of Oracle Server, their then crown jewel, with basically no strings attached, just to get people on the bandwagon.
If you use a totally-permissive BSD-style license, you're stuck trying to charge for a support contract or custom plugins or something.