Thats a fair amount of assumptions there, including mine and my friends eating habits (which are on par or better than anyone in a major city besides someone who actually lives on or works with an organic farm). I eat beans all the time as do most of the people I know (probably too much sometimes), though this is besides the point. I actually leave the herb material in my oil when I cook with it, so I get plenty of fiber with my decarboxlyized material without any negative digestive issues.
It's odd to me that you've never heard of raw cannabis being unpleasant to digest, but I guess its a question of degrees. If you want to eat raw oats you can do that as well, but I would not recommend it by any means because if your not very used to eating raw foods then it will make you sick (stomachache etc). More acid in your stomach isn't the best thing either, though again its mitigatable with minimal effort. Also there are a large number of people who have medical (digestive specifically) reasons for consuming, many of which limit the immune and digestive system and make extra taxation an issue of concern. I know that while I still eat them, my doctors recommend that I don't consume raw vegetables because of my own condition. I have heard many reports of people getting upset stomachs and unpleasant experiences with ingesting raw herb both before and after Ive started cooking with it myself, and I have several acupuncturists and other health pratictioners that rave about my decarb'd oil with whole material left in.
It's worth noting that the THCa will break down to THC naturally through the curing process, and will continue to do so when exposed to any air, so if your cooking with dry and brittle material the chances are that it has already been decarboxylated by storage conditions and nature which could easily lead to the conclusion that decarboxlyizing is unnecessary.
You touched on taking enzymes to help digest raw material, which illustrates my point that there is extra stress that needs to be mitigated within the body by supplementing your consumption with something else. By decarboxylizing before ingesting, you save your liver an extra step in breaking down the acid for your body to process.
THCa does appear to work on a different receptor pathway than THC according to the article, but that articles main focus seemed to be the creation of similar positive effects to thc without any psychoactive properties, and it only addresses two aspects when THC is known to have much more than that. Also, that test is done in lab dishes etc based on the abstract, which ignores the processing that occurs in the body (THCa gets broken down to delta11 thc in the liver, so it would have a very short window for any positive effects whereas the abstract was remarking on long term effects). So while it's interesting, I would need to see more information before I would be interested in THCa.
Aero18, it would be interesting if you could try a batch of watercured material in the bong with hot and cold water to see if the results are any different from normal materials. That nasty smell could be chlorophyll or something similar, Ive had to feed that to my pets before and it smelt very unpleasent.