I don't carry SA revolvers, in fact the only ones I have right now are black powder. However, I see nothing wrong with those who chose to carry this way, and in fact, they have enough advantages that I could see getting a 3 1/2" Sheriffs Model one of these days and putting it in the rotation.
They are big, yes, to control the powerful rounds they can hold. They are trimmer and lighter though than most other guns that are chambered for the .45LC, .44mag, .44spl, or that can handle full house .357mag. They aren't any harder to conceal than a S&W L-frame, and certainly easier to conceal than a S&W N-frame, big DA Ruger, or large frame Taurus. In a gun that is big, but reasonably concealable, you can carry 5 rounds (or 6 in a Ruger, Taurus, Freedom Arms, or Beretta with modern safety features) of some fairly potent handgun rounds. With a good holster and belt combination, most people would be able to carry a SA revolver.
The Colt SAA, clones and tributes have a grip design that many still consider one of the best ever made. They point as naturally as your finger. Most people can be quite accurate with them, and the guns will do their part if you can do yours.
Slow follow up shots? Not really. Sure, you need to train with it to be proficient, but that is true of any gun. If you shoot one handed, the recoil puts the hammer right back under your thumb for easy cocking, and you can get pretty fast with a little practice. Use a two handed hold and cock with your left thumb and with practice you can shoot it as fast as any modern handgun.
For some people, a SA revolver may make the most sense as their carry gun. If you shoot CAS or SASS you have probably invested a lot of practice and training in shooting your SA revolver. You will probably be more familiar with your SA revolver than any other gun you own. Under stress, we revert back to our training. If you carry a DA revolver instead of a SA, most likely you'll find yourself manually cocking the gun and shooting it SA anyway.
They are immensely reliable. Many people cite the reliability of a DA revolver as their reason to carry one over the more modern and higher capacity (and more easily concealed) auto. Well, a SA revolver has even less that can go wrong than a DA revolver, and many of the more modern designs are more reliable than any DA revolver.
OK, they only hold 5 or 6 rounds. That is true of many/most revolvers. When I'm in a state where I can carry I usually carry a J-frame which holds 5 rounds of the much less powerful .38+P.
Slow reloads? Yes, this is its biggest disadvantage. However, I wonder how many CCW holders actually carry an extra mag or a speedloader. Then, how many who do actually practice enough that they could reload a DA revolver reasonably quickly in a self defense situation? Personally, I find a backup pistol of some sort to be more practical than carrying a reload: they are faster to deploy, and should something go wrong with my primary, I still have a gun to put into action. Finally, FBI stats still say the average self-defense shooting will end in 3 shots. While one can always be one of the outliers, the chances of needing a reload are quite low.
Are they necessarily the best choice? No. Are they a bad choice for most of us? No.
If you are a cop and may have to go charging into an active crime scene, you probably don't want a SA revolver. For non-law enforcement self defense use, it can be a viable choice. In fact, it can be a pretty potent defensive weapon. Some people prefer SA only autos, others like DA/SA with the old S&W frame mounted safeties, others like DA/SA with a decocker only, others prefer DAO. Some of us like hammers on our autos, and others like strikers. Some of us like DA revolvers, and some people carry SA revolvers. It is a personal choice. Pick what you are most comfortable with. However, any of these choices will do the job if you can, and I see no reason to disparage the choices of those who choose differently than I do.