CBODY67, my 300 had the thick piece of foam hose to which you refer. It's visible in the before photo between the steering box and the metal coupling thingy (gear connection?). I agree with you that there may have been no wear on anything, at least theoretically, however, after 258K miles, my high-pressure hose with the foam hose over it had worn through the splash shield and was wearing on the inner fender. That's why we went with the two clamps to hold it securely off the splash shield. Maybe not "correct" but an improvement in my book nevertheless.
For whatever reason, none of my cars (4 of them) had no problems as you describe, using the OEM hoses and routing. Even back then, aftermarket hoses from noted aftermarket suppliers all seemed to be a bit different than the OEM hoses, naturally.
You upgrade mounting is a good one, but one which could have been problematic on the assy line, both in cost factors and assy quality, I suspect. Especially since the stub frame and engine were assembled as a unit before they were mated with the body from underneath. Another "labor operation station" would have been needed, which would have increased production costs. So, what might look sloppy gets to be a cost issue, obviously.
In looking at the hose on the '66, back when it was just a used car, I discovered that by clocking the gear pressure fitting more toward about 12:30, it caused the rest of the hose to move toward the gearbox, too, making a tighter "U", which kept it away from the body sheet metal and suspension pieces (which had the rubber shield covering them). Everything "draped" nicely and "in open air", too.
Same orientation on the '70 and '72 C-bodies, too.
At this stage of the game, with a greatly-diminished number of good, OEM hoses, "Whatever works".
Just my experiences, which might not match those of others,
CBODY67
