Totally agree.
I've been playing guitar for nearly 17 years now, with 8 years of classical piano and 7 years of trumpet and one or two years of percussion. Guitar is the only one of those instruments that I don't feel obligated to be able to read music. That's not saying I can't, but I much prefer using my ears to create, or play music on the guitar instead of following along on the sheet. I do also think tab has made life easier for beginning/learning guitar players, but I personally despise tab.
Having a strong background in music theory has definitely been beneficial to my guitar playing, but I wouldn't ever say I rely on it for my playing. Granted, I play for myself and have not played seriously with other musicians for many years now. Even when I did, the ability to read music was the last thing on our minds.
Bottom line, if you think it could benefit your playing, it shouldn't be considered a waste of time. It's also not for everyone, so it's really a matter of preference. I didn't have a choice as I was forced to take piano lessons starting at a very young age and reading sheet music just naturally carried over to the guitar, but I definitely consider myself lucky that I was forced to take all of that training now that I look back on it.