Most, if not all aquatic plants grown by quality companies (eg Tropica, etc.) are grown emersed in greenhouses.
So *somewhere* along the path from them to you they are put underwater.
My opinion is that I'd rather it be me that puts them underwater in an environment that's good for the plants instead of at the local lfs which in most cases does not always have the best setup to care for plants...
I guess we're lucky over here. When I order a bunch of Tropica plants at the store, they arrive to the store straight from Tropica for pickup!
Now if I was receiving healthy plants from another hobbyist, then I'd prefer submersed since they've already adapted in a healthy environment.