Martinjmpr
Wiffleball Batter
IMO the two biggest reasons manufacturers (other than Fiat) don't do removable tops is safety (as Martinjmpr already mentioned) and noise/heat/cold as the removable tops would be unusably heavy if they were insulated like fixed truck cabins. Not many people nowadays would put up with it, they're too spoiled by quiet, cool, and warm modern cars and trucks. As has already been said, no matter how much folks on this forum like them, two-door removable-top 4WD vehicles are a miniscule niche in the new car/truck market of today and Fiat/Chrysler already has the lion's share of it captured.
My only disagreement with the above is the term "nowadays."
As I said above, it's always been that way. Particularly when these vehicles were new they rarely had their tops taken off which is why the makers eventually deleted that option.