I know* that their is a rule that says you can't apply an ability (like flaming, bane, holy, ext.) without it also being at least a +1 weapon. Meaning that the lowest level special magic weapon you can get is 8000 instead of 2000 (big difference at low levels.)
I also know that some people house rule away that rule, so they can get an item with a special ability for 2000 gp, which is fine.
But my question is WHY are the rules like that? Is it for balance? Is it to represent that an item must be magic before it can be "very" magic? Why?
*
http://www.d20pfsrd.com/magic-items/magic-weapons wrote:
A weapon with a special ability must also have at least a +1 enhancement bonus