If you really don't want the information (even encrypted) to travel over networks you don't control, then you probably can afford SD cards or USB sticks or more esoteric special constructions.
Can you elaborate on why you feel a need for such physical media?
Maybe it's not perceived the same way in the USA, but in Europe, most people who use cloud-services find it increasingly difficult to trust american cloud-services, thanks to the NSA. Hence why I'm looking for alternative ways to share sensitive information, programs, documents, you name it.
There's of course also owncloud, which is nice enough, but let's just assume that some may not even have access to the internet in the first place.
So, with respect to the point you made (make no mistake, it's a very good point), I say that there are scenarios that justify need for physical mediums to share data.
That said, I agree that sensitive or not, we really shouldn't be sharing everything over only a handful of communication channels (typically home & work broadband connection + mobile phone data connection). It makes surveillance all too easy.
This is where I think smart people could make a difference. When I want to share data with someone in the same location as me we should really be talking P2P only. It wouldn't allow NSA & co to get the same full picture as easy as they can now with central data hubs and only a few communication channels.
I guess you could say I'm merely planning for the future. Not that I wish that I'd ever actually have to go about sharing data via physical mediums, but I wouldn't exactly bet on it.