For me, adequate penetration is my first priority. I want more rather than less. If penetration is not adequate to allow the projectile to touch or pass through vital organs and important nerve centers, the outcome is likely not immediately good, or perhaps even after the fact. My long time experience with full wadcutters is that given adequate velocity, they are good penetrators. What is damaged or destroyed deep inside the target is never a guaranteed thing, which is why I tend to prefer more than one bullet strike on the target! That increases the odds of the preferred outcome. I do not and would not recommend a target loaded full wadcutter as a good choice for personal protection. On the other hand, 850/900 fps with a hard cast full wadcutter from a 1 7/8" barrel snubby will definitely qualify for my recommendation. I have not found much expansion to exist in most .38 Special loadings, even some of the premium ammo examples loaded to +P pressures. So for me, a full bore sized hole as far as the bullet travels is what I want. Remember that expansion results in even more diminishing velocity and thus penetration. That said, I am personally aware of quite a few times when a target loaded full wadcutter got the job done!
I have seen the results of an expanding bullet that did not penetrate to the vitals on both humans and animals. A very serious wound was the result, but it certainly was not immediately deadly. Physics is physics, and the laws of physics cannot be changed. We all have limitations, and those are different for each of us. I want a round fired from a handgun that I can control and shoot very well, including rapidly, and also with which I can practice enough to maintain my shooting skills so as to give the best accuracy I can personally manage. Remember that many of us are not as young as we used to be. We cannot see as well as when we were younger, and we do not have the hand and body strength that we used to have. Some of us have arthritis or other maladies that handicap our ability to fire and function as we used to be able to do. I still want to have my personal protection with me at all times, especially as I get older and less physically able.
Others may be able to handle a more powerful platform than I, but I want to be able to handle the most powerful platform that I am capable of handling. I have seen far too many folks over the years who were trying to use a handgun that was simply to big and too powerful for them. Their efforts were not nearly as effective as they could have been. I'm way past the time when "macho" gets it done for me. I want to be effective! So I shoot handguns and ammunition that gets it done for me and I am still effective. I am also still determined to get the job done without hesitation. Effective self protection involves so much more than just the equipment we choose to perform that task. I try to remember that all the time and I try to be ready to deploy if that is called for! And I am very happy with my choice of handgun and the ammo that I carry in it as well. When the flag flys, it's always somewhat of a crapshoot with no guarantees. I'm ready to take my chances with that!