You are right a full size has advantages. I do not personally believe they are that significant in a carry pistol. Or to put it another way that the smaller guns put one at a great disadvantage. I and most people who practice (as always training will have more of an effect than two inches of barrel) can shoot a compact or even subcompact well enough for SD purposes.
In terms of velocity vs barrel length based on all the chronograph numbers I have seen I do not believe than an 1" of barrel length or even 2" is causing enough of a reduction to be significant and certainly not enough to put me at a major disadvantage. If that minor difference is notable I had better strap on the glock 20 because there is more of a difference in performance there. Or perhaps I should jump up to a .44 mag or .454 causal. After all my firearm is the most important piece of equipment I carry and I ought to be willing to make adjustments to carry the most effective pistol I can. Concealment is simply a matter of trying harder. I believe it would be legal in Utah to carry a rifle. Why not just strap an AR (in 6.8 of course) to ones back. If one is willing to carry a gun and kill a person one ought to be willing to throw a sling over his or her shoulder, no?
Seriously though, there are trade offs in the choices we make. For me personally a 3" 45 or even a 2" .357 mag does not strike me as a huge disadvantage as a carry gun provided the person carrying it can manipulate it and shoot it proficiently. I would agree that if one could only proficiently use a full size that is what they should carry. I also don't believe that will be true for that many people provided they take the time to train with their weapon.
Your reasoning that your wardrobe has had more influence over your life than the size of gun you carry sounds like the antis saying the odds of you needing a pistol are so small, you might as well not carry at all.
It may sound that way but only if you ignore one of the key premises. I can carry something else that I can shoot well. That is the major difference. As I stated earlier if it was no carry or full size all the time I would go full size. That is a false dichotomy for most of us however, and not a situation that I face.
I might add that changing one's whole life and daily regime based on what really is the incredibly unlikely event that you will A) need not only to use a pistol but that a small difference in bullet velocity will determine the outcome sounds like unhealthy paranoia. I say that as someone who is as pro carry as one can be. Further my end justification to carry is not based in needs at all, it is a matter of rights.
Now you might well counter that a simple change is dress has very little effect in your life and you might be right on the money. One of the common features I notice on this board is that people project their lives/circumstances on to everyone else. Hence you have some people insisting a rifle cannot be used for HD because they live in an apartment with several shared walls or such things. Dress is significant for me. Do I believe it must be for others? No. Dress in mumu if it doesn't matter to you and it lets you conceal what you want. Recognize that others wouldn't be caught dead like that though and given their lives their logic is just as reasonable.
In short we have to agree to disagree but I do not feel disadvantaged by a smaller .45. There are a great many people who carry much less than that. If we were talking .380 vs .45 I would side much more with you.