When I shoot a deer with my .454 Casull, I know that no matter where I hit it, and at what angle, that it is going all the way through and out the other side.
Using a round with enough penetration to make "Texas heart shots", that
you can shoot accurately, does increase your options for what is a viable shot. BUT, it doesn't remove the "margin for error" in my opinion.
A gut shot deer is a gut shot deer, no matter if its shot with a .357, a .454. or a .458 Win mag.
Deer have been killed with everything from the .22 on up. A lot of deer have fallen to muzzle loading rifles and pistols, many of which have "only" the power of a .357, and some not even that.
The most important thing is, and always has been, what the shooter can do with the tools they are using. Bigger more powerful guns expand one's options, provided that the shooter can mange them, but they won't turn a bad shot into a good one. Many people can manage them, some cannot.
"Magnum Smurf" fell in love with the 7.5" Redhawk .44 mag. I think that's wonderful. If that lady's introduction to the .44 Mag had been a 10" Contender, with a beautifully blued, pencil thin octagon barrel, I can virtually guarantee she would think long and hard before even touching a .44 Mag again!
In the hands of an expert, everything works. For those less expert, there is such a thing as both "not enough" and "too much" gun. And there is more than just the ability to shoot accurately on a range that factors into which is which for any given shooter.
If you want another plus for the .357, if needed, it is considered a better choice for self defense than the big .44.
Why so, other than bulk and weight to carry?
Why? Generally speaking, in a self defense situation, the ability for fast followup shots is considered an important thing. The recoil of the .44 Mag in most guns works against that, a considerable amount more than the recoil of the .357 Magnum.