Our particular Norcold is frost free for some reason. No frost forms in it's fresh food or freezer sections except for, eventually (after several weeks), some frost on the cooling fins.
I can force our freezer to sub-zero if needed - but it's not needed by us.
More capacity in the same space I've never looked into or noticed ... as our capacity seems generous as designed in by Winnebago per the size of our rig.
Minimal fire risk could be an important consideration if absorption refrigeration fires were "common throughout the RV world". I hope I never have one. Propane refrigerators have been used in cabins and homes for decades ... I assume mostly safely. I stayed in one for a bit last year and it's propane refrigerator seemed to serve us just fine.
Cost may be a main reason for replacing an absorption RV refrigerator with a compressor one. If one is willing to give up some of the off-grid advantages of not depending upon constant and somewhat intensive electrical sourcing, then compressor refrigeration can be made to work in certain environments. It depends upon what style one wants to use for their camping.