I would agree it is not worth installing. While cooler oil might be benefitial for extended oil life, you still need to at least get the oil up to operating temperature. Does this oil cooler kit include a thermostate/bypass to ensure the oil at least gets to operating temperature? It is important to get oil to temperature to evaporate any water away and properly lubricate the bearings.
As for when you would need an oil cool? Well, if you are using oil to help cool the cylinders in a very high power application (for example, you are using oil squirters on the rods and make 800+hp), then it might be a good idea. Another good situation would be road racing, where the engine is continually under high loads and is at the limits of cooling, but you'd never see such an operating condition on the street or strip.