Falcon - they could have, and later did. Its called the .45 Auto Rim.
During the war, to have produced a different round completely would have required setting up a totally separate line or lines, not just what ever it took to add the stab crimps, or simply using the existing .45 Colt cartridge. They certainly would not have gone to .38s, for example, so few years after adopting a .45 because of the poor combat performance of the .38s in the Spanish American War and the later skirmishes during the Philippine Insurrection, against the Moros in particular. Further, in an emergency, auto pistol ammunition could not have then been used at all in the revolvers, or conversely. Further, the idea of clips in the revolver was militarily very sound. Easier to carry ammo (the standard pouch, and I am recalling this from years ago when I collected that stuff, had three pockets that would hold two clips each, for a total of 18 rounds, only three less than were issue with the auto pistol.) The rounds could be loaded three at a time. much easier and faster than pulling individual rounds from shell loops on the belt, or from a pouch, and loading them one or two at a time.
These revolvers were usually issued to rear echelon personnel, not that none of them saw combat. However, oddly, I have seen more pictures of the 1917s in actual combat use, especially in the Island hopping by Marines, in WWII than in WWI. Of course, more pictures were taken in actual combat in WWII so that might not really mean much.
The revolvers were needed because Colt, Remington-UMC and Springfield Arrmory’s auto pistol production lines could not met the demands for the pistols. Colt and Smith and Wesson had perfectly good revolver lines sitting pretty much idle (compared to the production of other items for the military) and were able to fill the gap with existing machinery (with additions and revisions of course) and pretty much existing personnel.
The only reason civilian, by and large, don’t like the idea of clips is that they cost extra and it is hard to get the cases out of them sometimes, to reuse them or for reloading the brass. Still, they received some use in competition. Civilians, though, buy and large prefer speed loaders for revolvers in competition or if carried for self defense, especially in the U.S. where revolvers still have some following, although it dwindles from generation to generation…