Sure, why not? Paying 27,000gp~ for a sword that does an extra 2d6 damage that most creatures will resist/be immune to by the time you can afford it is a bit underwhelming. It's an interesting idea for creatures that are weak to whatever you enchant the sword with, but that's what they made the bane property for.
You know, I asked this same question a while back. There really isn't anything in RAW to directly oppose it, but it can open a can of worms with certain special abilities such as Spell Storing, Merciful, and Valorous.
I thought I read in another thread, that elemental effects like these can be combined, but they had to be individually activated, hence turning the previous one off.