I spent years with no theory knowledge whatsoever, I just knew where the notes were on the neck. I spent all of my 20s more concerned about my hair onstage than my musical knowledge. The rock music needed no more than half a dozen notes per song, and the simpler it was to play, the more I could prat around onstage. I got the root notes from the guitarist and just followed that for 90% of the set. I've been in a covers band for the past decade and love it. I have spent extensive time working out great musicians basslines from youtube or crappy tab, and only in the last year made a point of sorting my playing out properly.
Before actually learning properly, and I didn't really realise this until I knew otherwise, I didn't learn songs, I just spent hours memorising extensive sequences of notes. I had no knowledge about relationships between notes and why some sounded good with each other and some didn't. My ignorance made learning songs incredibly time consuming and arduous.
Only once I had some lessons, understood some theory, learned some scales did a light at the end of tunnel appear. My tutor was amazed how I'd managed to get by and learn all these songs without understanding a single thing about music.
I'm no Jaco yet, I have a ton to learn still, but I understand my majors, minors, pentatonics, blues and few others, and it has been life-changing and that's no exaggeration. I can pick up a bit of a track by ear and now work the rest out from knowledge of theory.
For years I just couldn't be bothered to learn it properly, and now regret not doing this sooner. I was too concerned about rocking out, getting the girls and looking cool.
Everyone should learn, you're only limiting what you can play, how much you can enjoy what you play and how much time you have to spend working tracks out...