Peacock...
Some people don't WANT to be bothered to sit and learn sleights, routines and the likes from books or DVDs containing lots of material... they just want the quick, easy BAM! approach of a one-trick-pony.
Like Jordan says, a lot of these effects actually teach you a lot (someone actually bought NFW! off me a while back and wanted to tell me how much it had taught them!)
Also, single effects these days are MARKETING driven. It's like the sugar and salt in MacDonald's food... you KNOW it's wrong, and naughty, but you keep going back for more. Ellusionist, for example, are masters of the art.
So you see, it's easy to understand. Simple Human Nature.
NOT!
