Wish they would! I used to own a 1984 Nissan Truck (that's what it was called) that was based on the old Datsun small truck platform. It was a wonderful little truck, perfect for somebody who wasn't hauling tons of construction supplies around. Unfortunately that truck went the way of all automotive products, and ended up in a junk yard after I drove the wheels off of it (it lasted until the year 2000, and had over 250,000 miles on it). I'm a fan of small trucks, and have been saddened to see them virtually disappear from the US marketplace. Fiat makes a little truck, the Strada, but doesn't sell it here in the US (yet, I hope). Autoblog has a great little overview of this great little truck -- anybody from Chrysler-Fiat who reads this, please bring this truck to the US market!
Related: what killed off the small truck segment in the American auto marketplace? This article over at The Truth About Cars website offers a theory. Another example of government regulation affecting the options available to consumers.