You start with a false premise. You don't hear people talking about their unmodified jazz basses because there's nothing to talk about. People talk about what they're going to change, not what they're leaving alone. I don't think anyone here has ever said, "hey, I just bought this cool Jazz bass. Over the next six months I'm not going to order any parts and I'm not going to swap out the pickups or the bridge." You only hear those sorts of things from people who do want to do things.
The jazz bass has one of the most distinctive sounds I'm aware of. It's also more versatile than some basses, so you can get more out of it and you don't have to stick with a traditional, close-to-the-bridge, burpy sound ala Jaco if you don't want to. You can do more with it. That, in itself, is part of why Jaco and John Paul Jones don't sound the same.
I'm not sure there's anything else to say about it. Some folks will modify anything because they like to tinker and others will do it because they're chasing a specific sound, and some are just never satisfied. But some folks, like me, think their basses sound just fine the way they are and don't have the urge to change anything.
...what rant?
