It really isn't that simple all the time. My Volvo runs corvette wheels and the spindles cant' be re-drilled that big. How do you correct that problem correctly?
In the world of Abody's yes, the most correct and ideal way to run wheels is a 4.5" conversion. I did this on all of my cars. So I agree with you.
I run spacers on my dart to get the perfect offset which is NOT available with wheels alone. Trust me every mm counts with my car. They are that tight.
Factory duallys run spacers so my point is there is nothing wrong with using a quality spacer/adapter. The good ones aren't cheap either. 300+ dollars a set.