No one is stopping some dude from taking a large chunk of MIT or BSD licensed code modifying it and then closing it off forever. That fork could become the one to use while the pre-forked one dies in a fire because the software is no longer compatible with the new shiny one with feature X. "Oh crap! I'd like to fix this bug that's been plaguing me since I switched over to the closed source one, but now I can't." -- Some sorry dude who used BSD licensed software
Those who say they don't care about this sort of thing are lying to themselves and everyone listening.
There's this stigma around the FSF licenses, which has never made sense to me. The whole point of them is simply "I share with you, please have some common decency and share with me." This seems like common courtesy to me, and only fair. If some corporation really wants to close everything up, well the same logic for avoiding Crockford's license applies, just rewrite it and don't use it. But, he who shares should always win.
: yes, this was a loaded argument.
I sincerely like the GPL and AGPL. I don't think potential confusion is a compelling argument against either, nor do I think it against the "do no evil" clause.