I care less about the "Doctrine of First Sale" and its application to digital goods than I care about the mile long trail of people on Twitter talking about their revoked keys, missing refunds and other crappy business practices. Well, that and my own experiences.
Sell blue jeans is perfectly legal but if a company sold me blue jeans that fell apart, required an extra surcharge to guarantee them and would maybe go missing from my closet without warning and then take weeks to be refunded or replaced, I'd still take my blue jean shopping elsewhere.
Oh bitch, please! - I'd start buying dresses and kilts, if I had such bad luck with jeans!