My beef with the 5x4.5 pattern, using Dana 44 with 5x5.5 pattern as the good example:
From the bolt pattern, you need ~1" of material inside of the bolt holes to ensure adequate strength = 3.5" centre bore (more/less)
If you allow ~1/4" material for hub thickness that leaves ~3.0" for bearing - commericially available bearing Dana 44 uses outer location has 2.891" od. and has 1.625" id. (~1.25" delta)
This thickness of material allows splines to be cut into the hub - allowing the disconnect mechanism to be internal. And disconnect is relatively small part.
The original 19 spline outer stub axle, had 1.245" od. Meaning there was at least 3/16" of good 4140 steel all the way around the spindle.
This combination allow the inner and outer bearing to be properly spread apart.
But when you have 5x4.5 pattern and you subtact 1" material, you get 2.5" center bore on wheel.
If I allow 1/4" material for hub, you are down to 2.0" o.d. bearing.
And you can guess that a 2" od bearing is going to wind up with id way too small for a spindle which allow any size of axle.
Ford's solution was to mount the bearings side by each in the hub where they are too close together to have proper strength, so Ford has to increase spindle od on Dana 35 from that of Dana 44 to 1.781" - which results in corresponding od increase to (3.0625").
Then Ford needed the "hat" to fit the disconnect mechanism into.
The "hat" means that the rotor had to be cast into the hub - so if you damage the rotor, you have to replace both the hub and the rotor as they are a single part. Wear parts should be kept separate from rest.
If they had upgraded 4x4s to 5x5.0" (I know Chevrolet pattern), they could have had a Dana 44 style solution which would be stronger. I don't think they saved any money with the smaller pattern because of the "hat" isn't inexpensive. And a Dana 44 style solution would allow for larger tires.
Things even get worse in the IFS - the wheel mounting surface is cantilevered out from the bearing - hence the unit bearing is effectively a 4" od bearing.
Of course, some place in there fuel economy became significant driver = flush rims and cantilever mounts are ideal for mounting them.
There got it off my chest.