The .357 Magnum is not a practical pistol round for defensive sidearms intended for anti-personnel use. This is for the large majority of those who own firearms and not those who are highly skilled in their use. Even that group may recognize the disadvantages of a low capacity weapon with high recoil and choose another system more capable.
And here are the reasons.
While you’re sending that master blaster round downrange it had better hit the target since it is very difficult to get a fast second and third round going toward your target before your target has a chance to respond. It is quite possible to make a great first shot if you are dealing with a target that is nearby and standing still. That said, if you deliver the first shot with this weapon and hit center mass then the results are likely going to be astounding and immediate. Slow recovery for a follow up shot is something you can train against but the laws of physics are hard to overcome. Overall, you could put four or five 9mm rounds downrange while only sending one .357 toward the target.
To handle such a round you generally must have a heavier weapon. If it is a nightstand gun then there is isn’t a problem but if you have to carry it day in day out then it becomes one. If you are in the back country and want a weapon for wild animals then maybe it is worth it to carry that extra weight but then you might even go for the .44 magnum.
Do you want to lose your hearing? Fire one or two rounds of .357 magnum without ear protection and I can almost guarantee you will be get permanent hearing loss. I’d rather send multiple lower impulse rounds downrange from a .38 special.
Limited Number of Rounds
Generally in some of the best revolvers for the .357 you can get a maximum of 7 rounds though usually six. I tried a S&W 686 that has that 7 round capacity and it is a superbly accurate and reliable weapon. When facing one opponent 7 rounds is generally sufficient, but for situations with multiple targets I would feel at a disadvantage if my opponent were carry any one of the many guns capable of carrying 15-20 rounds.
The 357 magnum is proven, reliable, and effective within the foundational needs of close range defense but there are severe limitations. Owning a weapon that allows you to download to .38 special with reduced recoil and muzzle flash can give you the flexibility of faster recovery, less noise, less muzzle flash, avoiding over-penetration. Using a weapon designed for a .357 magnum and instead loading it with .38 special is a long time means of taming the recoil and of course giving up the major advantage of the round that is a very effective stopper. When in bear country you might be able to justify carrying the .357 with a heavy bullet as your last ditch defense and at least you know the bear won’t be shooting back. In an alley where you might have multiple assailants I might consider the same revolver but I would much rather have a faster recovery for the next shot.
Generally though, I would opt for a wonder nine capable of holding 15-20 rounds. I’d rather have a weapon that sends projectiles to the target that does not hinder my ability to engage multiple targets quickly or to deal with a moving opponent where I may need repeated shots to get a hit. This is best done with an auto-pistol in any of the major calibers from .380 on up to .45.