I agree with you here that the round nose lead bullet (RNL) did develop a poor reputation (though it was used for a very long time by law enforcement). But I believe the reason was the bullet shape and form and not so much the loads or the guns they were fired from.
I don't think bullet shape is enough to explain it. The RNL configuration was no different than bullets that had been in use, in the .38 and all other revolver calibers, for over a century. Wadcutter and semiwadcutter bullets had been around a long time (the first wadcutter, the "Himmelwright wadcutter" was introduced in 1900); if they offered a noticeable step up in performance, it's difficult to see why they would not have been widely adopted for police and other defensive use. They weren't. The somewhat sharp shoulder of the wadcutter might make for a
slightly wider permanent wound channel, but not much. Non-expanding bullets all make simple, narrow tracks through the body, unless they are launched with enough power to tumble or fragment, which they're not out of
any .38spl, snub-nosed or otherwise. If a bullet like that hits the central nervous system or a vital organ, it will kill you, despite being low powered. And as I've said, even a lower powered bullet of this type, like the old .38spl RNL, or the .41 rimfire derringer, or the .38S&W, or many other old cartridges, were used for self defense, because there were no better loads to be had, and they could be fired out of compact, easily concealable guns. But concealed carriers then made the same tradeoff most of them still do today: they give up some power for the benefit of having a small gun that can be concealed and taken where a large one can't. For most self-defense shootings, this is a viable tradeoff, given the short ranges, and lack of body armor or cover in most such shootings. None of that means for an instant that those old guns, and some current ones, aren't very underpowered guns that will have a lot of trouble penetrating even very light cover, should it be encountered.