I think it's a symptom of the TJ being mostly an enthusiast vehicle, and something that tends to happen as cars age out of the utility market. I would guess that the typical JK/JL owner uses their Jeep more for utility transportation compared to the average TJ owner. The majority of drivers don't want to ever think about nor care to know about how their vehicle works, they'd rather just pay money to get around in something that looks and feels good. When it gets to be a headache, they'll move on with something else. Enthusiasts, on the other hand, welcome the headache by finding some weird little niche and diving in wholeheartedly. Memorizing part #s, collecting parts for spares, and going to bed hoping at least 2 of their 7 bids on Ebay go through is normal behavior.
And it's not just a Jeep thing, I'd bet the average owner of a 70's-era BMW 2002 tii can tell you the # of bolts on their intake manifold whereas the the owner of a late model 3-series probably has little to no inclination to ever pop the hood.