One could spend a lifetime on one style, I never understood the motivation to jump around. But then, it's not me or my choices, people do what they think is best for their own development.
There are many styles I'm keenly interested in but I want to stay contained to the few things I grew up with ... and maybe ad Kenpo, because that just makes 4. LOL.
I'm not interested in 'jumping around' or in collecting belts - due to my late-in-life start, I won't even earn my first black belt until I'm well into my 50's anyway. But I know that my style (Isshin-Ryu) does not have a particularly strong ground game, and I am very poor at falling properly as well, so I would like to supplement my training with some formal training in Judo at some point, probably in the next year or so. As you said, it's more for my development, I'm not interested in pursuing a belt in Judo; I just want to learn some of those skills, which I see as valuable.