[hanimal]

As people have said, no need to learn how to read music unless you want to be a classical guitar player/really take your musicianship to professional level.

Still, so many great players don't know how to read music.
I think taking the time to learn how to sight read could be better spent doing other things on guitar depending on what you want.
If you really want to be a dedicated, well rounded musician by all means learn to read music, but with tab, it's easy to be a good or great player without reading. Guitar just works in such a way where you don't need to.

It's definitely awesome to be able to read music (and can give you the bigger picture and more of a love for music overall) but if you just want to keep it casual, really no need to.