It's not the $4, the $4 is just revealing GW's motivation (i.e. not making a better game). They could be free, and they'd be just as destructive from a game perspective. (they are free, effectively, btw, anyone who wants a digital GW product for free can get it).
I mean, what if I Copy and Pasted some fluff, and wrote a 2 line rule that let you take those White Dwarf Flmaers of Tzeentch (y'know, with the AP2 wounds on 4+), but with, I dunno Hit and run, and charged you $10 for the privilege?
Would that be OK? Would it be legit? WHat happens when GW does the same thing? Is it OK? Is it legit?
Sometimes you just have to say "no".