That's another can of worms. If it were BSD licensed, they would not have made so much money, because they couldn't have done the dual-licensing trick.
Indeed, this is surely a price to pay, BSD will hardly make you rich even with a very successful product, but the project itself is much more protected probably.
When it's GPL'ed, there can be no proprietary forks. Companies who depend on the product will continue to maintain it and all source will still be available as keeping an internal fork is costlier.
If a program is BSD'ed, there is nothing to prevent a company to close it and start selling it as proprietary.
Proprietary forks are an illusion. The value of the project is in its developers, to take the code, close it, and develop it getting external developers, good ideas, and so forth, is a massive amount of work. This is why you can think of tons of BSD-ish very successful projects not forked.
Instead the real risk is that GPL is not free enough.
A proprietary fork can diverge very little, still grabbing the improvements of the original project. The reason you don't hear about them is because the vendors of such software have no incentive (and mostly no need) to say their product is mostly something they got for free.
I suspect they are more common than we know.
In essence, the only freedom GPL forces you to give up is the freedom to turn a free product into a proprietary one.
