I'll open this one, biggman100, it's a very important topic, however, I want others to share their views...
Basically, the urethane bushing industry developed around the high performance, tuned suspension handling needs of on- and off-highway vehicles. My first exposure was in the 1980s with the Baja race vehicles, 4x4 aftermarket lift kits, high performance muscle cars, Saleen and JBA Mustangs, and a variety of other high performance vehicle applications. There is a lot of misunderstanding around urethane, as it is not just "one material" but rather built to exacting "durometer" or hardness standards.
Modern suspension kit or engine mount bushings often have provision for "greasing" the bushings, and in these cases, make sure that the bushings are designed to accept grease from the provided grease fitting. This may sound elementary, but there are lift kits where the bushings are not designed with a grease groove yet the control arm sleeve or a similar part has a provision for greasing! This is the "grease fitting to nowhere", as the bushing cannot be properly lubricated in this manner.
And yes, urethane bushings do require lubrication at some point after their initial assembly with lubricant/grease. (Use a grease designed, ideally, for these bushings, although some manufacturers claim other chassis greases will also work.) If not greased, the bushings will squeak at the least and wear quickly at worst. Vehicle handling can suffer, too.
So, to be more specific, it's always best to get engineered urethane bushings with the right durometer for the application. I personally have relied on companies like Energy Suspension over the years, urethane bushings are their main business. Kits from companies like Energy Suspension, Daystar and others actually have design features for handling, safety, longevity and compatibility with a particular vehicle's chassis.
Will urethane bushings hold up? To a degree, and here I go back to the original design intent: high performance, quick service in the field or trackside, and special tuning for a particular chassis that gets reworked and rebuilt periodically. In general terms, unless you service the system (grease or periodically disassemble and lube the bushings), you will have a problem with product life.
By comparison, OEM bushings have no provision for service, they are lifetime "rubber" and designed for a cushioned ride, less noise, minimal vibration and less harshness (NVH). They have a duty cycle like your Dakota is experiencing in terms of lifespan under specific driving conditions. When worn out, you replace these OEM rubber suspension bushings.
I have more to say, however, it's important for others to jump into this discussion...Thanks for opening the topic, biggman100!