I started on bass as a kid some 30 yrs ago, but
I get by on guitar pretty well out of necessity as a composer/producer(but I play it "like a bass player" as I've been told, which is still better than playing bass "like a guitar player" I think

This has come in extremely handy in a couple ways.
Aside from the obvious that
it just makes you more well-rounded, I play most of my own guitar for demos and composing work rather than having to get somebody else in to do it--saves a ton of time and money(but if it's really demanding/critical parts I will hire somebody).
And, one thing that has saved the day(or at least a bunch of time) more than a few times at sessions---we all know how effective a guitar doubling a killer bassline can be, right? Well, I can double the bass on guitar, and match the phrasing dead-on and it is TIGHT. I'm not so much talking about rock where the bass is doubling a heavy guitar riff, but reggae, soul, RnB, where the bassline is killin' and has all the cool little qualities of a happenin' bass performance. Since I'm very comfortable getting good clean phrasing on guitar, I can double my bass part usually in one take. Makes producers very happy.
I feel the same way about keys----I think
any musician should have some kind of keyboard around too to get comfortable with--you won't regret it.