Folks like the .45 because it's a big case and ".45" has a certain flair to it but in reality, the .44Spl is the better cartridge for the platform. With comparable bullet weights, it can launch them 100fps faster and with a greater safety margin. It is also more efficient, requiring 15% or more less powder to reach the same velocity. At this pressure level, the big .45 case is a lot of wasted space. Regardless of manufacturer, the .44Spl also suffers far less from goofy chamber dimensions. While the .45 has long been plagued with oversized chambers and over or undersized chamber mouths. There are plenty of reasons not to choose the .45Colt in this platform and zero reasons for a handloader not to choose the .44Spl.
The .44Spl is also quite the historic cartridge. Its parents are the .44S&W American and the .44 S&W Russian, both of which preceded the .45Colt by a few years. Three years before Colt had it's .45 SAA, S&W already had a big bore centerfire cartridge and a military contract. The first big bore cartridge sixgun was not a Colt .45, it was a S&W .44! Even Colt's first big bore cartridge sixgun was not a .45, but a .44! S&W negotiated a contract with the Russian government and they liked their .44 but wanted an inside lubed bullet. So the .44American case was stuffed with an inside lubed bullet and the .44Russian was born. The first .44 that was actually a .43. Then in 1907 S&W lengthened the Russian case and introduced their finest sixgun/cartridge to date when they brought about the .44S&W Special in their First Model Hand Ejector or Triple-Lock model. A perfectly balanced cartridge for the S&W N-frame, Colt New Service and Colt Single Action Army revolvers. Then, of course, due in no small part to the writings and urgings of John Lachuk, Elmer Keith and others, the case was lengthened again to become the infamous .44Mag. That history, coupled with 80yrs of writings from folks like Elmer Keith, John Lachuk, Skeeter Skelton, John Taffin and Brian Pearce and the .44Spl is more popular today than ever before.
So yes, the .45Colt is a very historically significant cartridge but so is the .44 Special.