Agreed. Case in point: I'm (successfully) selling a JavaScript Game Engine[1]. It's trivial to steal the code, yet I haven't had any problems with "pirates".

Of course it depends whether you're talking about a "cool blinking mouse cursor trail" or a framework that takes a bit of understanding from the people who want to use it. The former will be "pirated" far more often, just because the target demographic isn't as aware of licensing and copyright issues (or doesn't care).

[1] http://impactjs.com/