Sure, I "play" lots of things, but suck at most of them, though I'm actually a fan of my guitar playing, and doing tons of keyboard playing in recent times, which i just LOVE doing. But I do it by force of will. In other words, if someone wants some bleeps/bloops/textures on their record/film/show or whatever, I'm all like "Sure! No problem!" The fact that I have some rad keyboards/effects/sound generating gear helps cover up for my limited skills, but thankfully I have an ear that lets me come up with some cool melodic/harmonic choices, methinks.
But i play clarinet (learned in school), and once in a blue moon, I'll do a session on either regular or bass clarinet....talking once every three years.
Learning, or even ATTEMPTING, other instruments most definitely helps. Can't speak on that enough, in fact.
JMJ