OK, here is my thoughts. If the ball is too high, and assuming that the weight of the trailer hitch lowers the trailer down enough to allow the trailer to be level, the entire hitch weight is borne by the rear wheels of the tow vehicle and the receiver. Technically that's a dead weight drop on the hitch. Most receivers and hitches are rated 2 ways. Once when used as a dead weight drop and used in weight distribution mode. Typical dead weight limits are 50% less than using the hitch in a distribution mode.
So let's take this a step further, why wouldn't we in our wisdom always have the hitch ball higher than necessary so that we wouldn't have to use weight distribution? Especially when the truck is rated to carry that weight?
Well first you have to realize that using a hitch in a weight distribution mode uses all of the suspension components in both the tow vehicle and trailer to carry the hitch weight. That makes both vehicles ride better and takes the stress off that rear axle of the tow vehicle when road issues occur. It would seem to me that more rear TV wheel road shock would be transmitted to the trailer due to a dead weight load. Secondly I think brake performance would be impacted in a dead weight situation since you could induce wheel lock earlier in the front brakes of the TV and trailer brakes since these wheels are carrying less load. Again the additional weight on the rear tires will probably accelerate some wear on the TV rear wheels. Less weight on the trailer wheels and front wheels of the tow vehicle provides less friction which may cause a decrease in traction overall.
I'm sure there are some other things I haven't thought of but that logically seems to be some of the issues that come up when you are using the dead weight concept rather than using the weight distribution hitch. In the case of having the hitch ball too high, even if you use the WD hitch, you aren't effectively transferring the load so that rear axle of the TV is still carrying more weight than necessary.
Is this a little more of what you were looking for Steve?
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700