Some comments here, and also off-list, helped me think further about these issues. The standard, often rancorous debate in literary theory circles opposes two ideas of reading: that it's a (sometimes desperately) solitary activity (Harold Bloom, some versions of Blanchot); that it's a cultural practice whose individual motivations may be analyzed into instantiations of cultural practices and demands (Greenblatt, Fish, some versions of Barthes, Bourdieu, and Foucault). I think both views are narrow.
I think that all literary experience (I parenthetically but emphatically include writing, too) is an experience of an audience (subjective and objective genitive at once: the audience's experience; having an experience of the audience's presence.) Listening to a story, going to a play or a movie, always includes an interest in how others are responding - even if the others are the laugh track on the TV show rerun I'm watching at home, alone, on a depressed afternoon (Zizek hears the laugh track as a Greek chorus, but the chorus represents the audience, or at least an audience). Those others are still there, even if only notionally, when I read in solitude. They're there at least in the form of the narratee, the figure I am brought to imagine as a naive or sophisticated or knowing or innocent reader of the work. I read the work over the narratee's invisible shoulder. I take pleasure in taking pleasure in the pleasure others take in the work, including what must be their pleasure in the pleasure I'll take, though it's probably important that I don't generally spell this out. Here my sense of the author's pleasure in the narratee's or perhaps in the (quote) "reader's" (unquote) response comes in as well. So to that extent reading seems cultural and communal, and though the narratee may be someone not just like me neither is he or she inscrutable to me.
And yet. The audience experience that I imagine, that I imitate, that I adopt, that I internalize, that I have is, at its most intense, and perhaps at its most most basic default-level, one of a solitary pleasure. Which means, I think, that solitude too (the good version of solitude offered by reading) is a social experience, and that social experience too contains solitude within it. I can learn and have learned from others -- through imitation of them and through imitation of what they've loved -- how to love the works I love. And a component of that solitary love is a desire to express it to others, to share it, to encourage or beg or demand or plead with them to experience it for themselves: read this, or watch this, it's just so amazingly great.
So I think it's not a bad thing to read for the sake of others (well, as a critic that's what my vocation is, isn't it?) - that is to say it's not a selfish but a sociable thing. Solitary reading is reading for others, but the genuwine article that we're offering others in solitary reading, in the most solitary engagement with solitary reading, is the experience and intensity of being drawn so far into one's own literary experience that one gets a glimpse at how essential others are to every moment of our lives.
I think this could be called the Wittgensteinian (and also the Winnicottian) account.