I think most of the tinkering is by choice...look at any of the "How Many Miles Does Your Jeep Have?" threads, and most say xxx,xxx miles, with just regular maintenance, and maybe one or two minor replacement parts.
The beauty of the Jeep is its simplicity. You can do the work yourself, and get advice from others who have done it.
You don't see so much tinkering on the Toyota Corrolla site, because thesy just bring it to the shop for regular maintenance, and don't talk to their friends about getting the coolant flushed or the oil changed.
Plus, my Jeep is ten years old with a hundred thousand miles on it, and that's considered young. Show me a car run for 10 years plus that doesn't need some tinkering once in a while...