Its true that a 44 mag gun will fire 44 specials fine.
Versatility is a good thing.
Very small minus of fouling the 0.10 of mag chamber.
Very small minus of velocity and accuracy lose of special in mag chamber.
Some weight reduction in most 44 special guns.
44 special is the superior round for a defense gun mostly due to recoil recovery.
Shorter guns are better suited for defense
Longer guns for hunting targets etc.

Thee 44 special has proven to be very effective and has a following. Similar to the 41 mag, why have one of those? Same frame as a 44 mag, really no special rounds. Less commercial ammo choices. But, the 41 mag has a following because many educated shooters find that it fits their needs best.

I have a couple 44 specials. I could sell my 696 no dash for enough to buy a snub 69 or a 44 mag. Won't happen. Traditional one piece barrel, no lock and I would only use it for a carry gun. Same short barreled gun in 44 mag would go up and twist more and be harder to get back on target, why would I need magnums for it.

44 special is like my favorite caliber the 45 Colt. Big heavy bullets don't really need the speed. The magnum speed gets you a bit flatter trajectory, but, what kind of trajectory are we talking within the distance 99% can fire a 6" or less barreled gun? If Fired accurately to vitals not many things are going to notice a few hundred fps when a 240 to 260 grain bullet wacks it. Over a 100 yds, the 44 mag is a clear winner, but until you get to there I just don't see any real big advantage.

Yes, I have 3 44 mags. They set in a drawer. Nothing wrong with them, just don't ever chose them for anything I am going do.