Why doesn't anyone ever turn that around?
Because they're afraid of challenge and ridicule from other fellow magicians.
Are the creators hurting the art of magic by selling the tricks in the first place?
Yes and No.
There are really two sides of the coin with this either way you look at.
What, exactly, does the art of magic gain from (say) Wayne Houchin getting $30 every time someone buys Control?
If my $30 is gonna go to the creation of a brand new 1-on-1/ DvD/ Deck/ Book every day, week, month or year, and these awesome forums, the I'd say there's a lot to gain from that.
I can see that the art has gained from Wayne inventing it, performing it, and teaching it. But what does the art gain from Wayne selling it? Why does $30 in Wayne's pocket make magic better?
"To help put food on the table, to pay for things, and blah, blah, blah."