I'd suggest that, in the same way as reading literature gives opportunity for enlarging one's vocabulary, so reading music (dots, Tab, whatever...) allows expansion of one's musical vocabulary. Listening to stuff does this, too, of course, but once past the 'Janet and John' stage of reading music (without necessarilly being able to play what is being read; just understanding it is enough, hearing it in the head...) a whole shoal of new worlds can open up.
I'd certainly differentiate between 'reading' and 'sight reading'. The first is available to all, without too much study. Not so the latter, which requires (and rewards...) much more practice.