When sending anything by post I would have thought it the most natural thing in the world to add the name of the recipient on the address, if only because it allows the household it arrives in to know exactly who the card is for. For me it's not so much an etiquette issue; more a matter of good communication. Having said that, how would I feel about receiving a card in the post when it was clear someone hadn't bothered to address me by name? I probably wouldn't be too impressed, if I'm honest.
If it is obvious who the card is for within the household then it's not really an issue because the right person will likely receive it, but then again, suppose the postman delivered it to the wrong address? Or suppose there was an error writing the address and there was also no name on the envelope, causing the card to become lost at some point in delivery.
It seems obvious to me that a name and address on any item sent through the mail is possibly the way to go, bearing in mind how much mail tends to get lost en route.
Also, adding my name on the envelope means the person is 'handing me' the card, albeit via a postman, which I feel is a more caring way of delivering the card. It has a slightly more personal touch.
Thinking about it, if a card was sent to me that contained only the words 'from Joe/Harry/Barney' or whoever, adding no personal touches whatsoever, it tells me they are sending me a card simply because it's the 'correct' thing to do. It tells me they are sending me a card because that's just what all people do which, for me, is totally meaningless. Who came up with the idea that everyone should send always send cards to everyone, regardless? Oh, wait, it must be card shops and card manufacturers because they are making a tidy profit on every card sent.
If the card was also not addressed to me personally either, without clearly showing my name on the envelope I'm afraid I would simply cast it aside. In other words, I would give it about as much attention as the attention of the person who sent it me.