I'm able both to read and to type in "day residue" dreams: those that are primarily based on prior events while awake. I've often had dreams which involve me reading and posting to internet message boards.

For dreams occurring on a deeper, more symbolic level, I haven't had the same experience, though I couldn't say whether that means I can't read in those dreams, or only that I haven't remembered doing so.

Perhaps individual circumstances matter. I was hyperlexic in childhood and to this day my preferred learning style consists of reading and/or rote copying, which I've learned is unusual.