Many rock crawlers aren't trailer queens and are driven to the location.
Billet aluminum adapters are no different than bolting on an aluminum wheel as far as I am concerned. I have ran them without issue and so has another member and he has a 440 in his A-body that is street driven. The early cast ones were poor design and quality which did lead to some problems.
It is amazing that so many of the 7 1/4s have survived and are still on the road if they are such junk. There no doubt anyone would rather have the 8 3/4 but some people don't have the money and even 8 1/4 rear ends are getting scarce. With either you still have to modify a drive shaft.