Let me offer this opinion: the 44 Special was created so that users had to buy a new pistol.
The main driver, in fact the sole driver of any new product is increased profits. Cartridges are introduced to increase profit, there are literally thousands of cartridges infinitesimally different from each other, as a class, and yet, more keep on being introduced. Is the new cartridge 100% better than old or nasty? Are they 10%, or 5%, or even 2% better? What a new cartridge does is get the customer to buy a new boom stick, reloading dies, shells, cases, etc. The whole caliber change over creates a lot of cash churn.
As anyone with an electronic device can testify, the change overs provide very little "improvement" but do require a lot of cash.
Driftwood has plenty of period ads, one of which was a S&W ad comparing various cartridge penetration in wood. Interesting that the 45 Colt was excluded. There were no velocities given, just penetration in wood, and as I recall, the 44 Special was a winner! You see, people and animals, are just like wood, so the more penetration in wood, the more lethal the round. The logic is irrefutable. Especially late in the 19th century. Today we know, the true index of lethality is penetration in plastic milk jugs filled with water. That is because milk jugs can be plucked out of recycling containers on recycle day, and are easily filled with water. Used to be the gold standard was wet newspaper and wet phone books, which used to be the trash at the curb, but no longer. I remember stacks of newspapers and phone books, all tied into a bundle with string, on the curb at trash day. Them was the days! The shooting community has smoothly and seamlessly moved from wood penetration (requires a table saw, drills, and screws to make the wood tissue stimulant) to wet newspaper/phone books, to plastic milk jugs filled with water. Tissue stimulant technology advances one garbage can epoch after another.
It is my recollection that the ballistics of the 44 Special are the same as the 44 Russian, a 246 grain bullet at 770 fps. So the change over to smokeless did not increase the velocity of the round. And maybe, S&W did not want to increase the velocity of the round. Other period ads I have seen, were touting the "accuracy" of S&W pistols, not the power. In a horsepower race the 45 Colt wins. At least in black powder form. You can look up Army 45 Colt velocities in the 1909 revolver, and Hatcher gives it as 750 fps (ish) with a 255 lead bullet. I have seen blackpowder velocity data and the 45 Colt in a balloon head case pushed the 255 close to 1000 fps.
I have no idea of the original pressures of the 44 Russian or the 44 Special, but given that late 19th century revolvers were made of unheat treated plain carbon steels, it is possible a smokeless 44 Russian would not have exceeded the pressure of the blackpowder round.
It makes sense to me, that if the customer base was happy with the 44 Russian, than introducing a smokeless equivalent made sense, and it even made more profit sense to create a cartridge that forced the customer to buy a whole new firearm, rather than something that could be stuffed into an older revolver.