I think you have some mixed up ideas on your post so lets figure them out.
First Im not at all against wild collecting, even for endangered species or species with a high degree of protection if the proper permits are obtained, the species is suitable to aclimation to captivity and the impact made on the wild populations is as low as possible (taking a hatchling insted of a adult). Hell MANY species have their continual existenc assured because they became established in captivity in THE PRIVATE SECTOR (zoos just take the credit for it and then call private keepers ilegal traders

)most are endagered to extinct in the wild, from Fidji iguanas which are becoming very popular in europe, to many extinct in the wild or endagered asian turtles. Actualy its funny how cites and other laws regarding animals protection are actualy endangering some species furter by not allowing people to colect them to introduce new blood into their colonys or species that have no captive representatives at all, like some Cyclura. They are protecting them to death, cortesy of our tree hugging buddys
Now you also state that captive populations can become higly inbreed which is true (even to some species naturaly have a small genetic variability) but it doesant necessarily has to be that way, if the founder number of animals is big enough and the several keepers are serious enough to exchange animals between them to assure healty genetic crosses, a inbred crossing aint gonna kill nobody either if only made by a few generations but new blood is allways better. If that aint possible then at least non healty animals should allways be culled out, and that is in my opinion what is endangering the captive population of blue tegus. To anybody that doesant know the story these are decendant from a single clunch of siblings. The prob is that the albino mutation apeared on these and people were so escited because of it that they inbred them to a huge degree, if insted they only bred completly healty normal animals (they could produce albino tegus anyway by cross breeding the albino gene into for example the argentine black and white) we were left with a population of nearly identical healty twins insted of animals with deformed jaws and other congenital probs. You said that yourself on the bearded dragon example, to my knowlege no new blood was introduced, however most nowadays beardys are healty normal animals...of course if Australia hadnt so overkill laws regarding wildlife trade our population of dragons would cernatly benefict from some new blood. Only a fraction of the number of beardys that are run over by cars each year would sufice...
Now if somebody comes here and says"can I catch this reptile", I will unevitably recomend going for a cb one, the person just wants a pet and wild reptiles can be much more dificult to aclimate and care for then cb ones. Some species like many snakes and turtles unless for new morphs are so readbly avaible that there is simply no reason to catch them and furter endanger local populations. Of course if the person is experienced and wants like to start a breeding program then its diferent.