We had the same concern so we designed each step of sending a card to be authentic - down to hand addressing the addresses on the envelope. You handwrite it all. But yes, you do skip going to the store and messing with stamps.
You are essentially sacrificing your product's value for word of mouth.
He very clearly mentioned that the response has been more warm and positive than negative. So it seems obvious to me that they are not sacrificing their product's value at all.
Maybe that's true so far, but I suspect the early-adopter users are more forgiving of a lot of things. The hockey-stick users might be less so, and IMHO they need to be looking forward to those.