ours came with them also, but only because the dealer ordered them from the factory, when they ordered it for their own inventory. they also ordered it with other options, such as the outside grill and fridge panels.
if we had custom-ordered our Roo, we probably wouldn't have added them. but we are so glad they came with the trailer we bought. we don't get to use them much, since we dry camp most of the time. but, when we do have electric hookups, man are they nice!
it's only an option if you're ordering from the factory. if the trailer already has them, on the lot, then the dealer ordered them.
like i said, maybe the higher priced trailers come with them but i suspect they are included only if it's in the order.