I agree with you.
While we always tout, the weakest piece of glass will be that cheap filter we put in front of our lens, some people may find it unreasonable (with reason!) to put a very expensive filter in front of cheap lens. I mean, sure, use that B+W filter with a $2000 lens will make sense rather than having spent $2000 on a piece of fine glass, then $20 cheap filter which will degrade the quality you can get from it.
On the other hand, $100 filter on a $250 kit lens is debatable. You have several options - use a lens hood and forget the filter entirely, or use a cheap filter... or you can also use that $100 filter on $250 kit. Everyone will have their own preference and it's not to sway you from one direction or another, but rather have you know the choices and implications, so that you can make an informed decision yourself.
:bsmilie: :thumbsup: :think: