I'm working on my reading and theory at the moment now. I'm partial to a bit of solo Bach, and whilst some is available in tab form, it seems somehow perverse (in a bad way ) to use it, not withstanding the fact that tab is a completely deficient notation system IMHO since it doesn't record the rhythmical aspects accurately and relies on listening to the music or having notation with it to resolve that problem.
Other than that, I enjoy the experience of learning in general, so natually I want to learn about music since it is one of my passions. I find it rewarding to improve my reading skills as this means I can start playing more music to a higher standard more quickly.
As far as theory goes, I'm interested in how it all works. That's reason enough for me.
I still noodle around, play along to backing tracks, jam and gig (only occassionally atm ) with the band, write new bass lines etc, I don't think any of it is mutually exclusive, it all contributes to making me a better bassist.