The main reason enthusiasts don't buy a dedicated /\/\otorola transceiver for receive-only purposes is because they want a single unit that will do everything with more mainstream programming ability. Besides, much of the time people are scanning multiple trunking types, some of which an actual Motorola radio CAN'T do. It would require carrying around not only your regular scanner but a second radio as well.
While I completely agree there's nothing finer than a Motorola radio, it just doesn't make sense for most scanning enthusiasts to do what you suggested unless they just listen to a Motorola-only system. Then perhaps it's a good choice IF the person doesn't mind acquiring the necessary RSS/CPS and programming hardware, and of course learning to use it. If a person were to fit this scenario then I agree you wouldn't find a better method to monitor it.
I completely agree but its just preference for me at this point. Once a good company comes out with something sweet I will buy a desktop unit too. Motorola radio is a luxury item for me. Uniden just has not shown their hidden cards right now. The scanner business is just dead