Not a bad question at all. Here's a few reasons, and I'm sure others will come up with more:
A long history, starting with the Triple Lock and through the Elmer Keith "hot-rodding" era and law enforcement use, and its lineage with the .44 Russian and the .44 Magnum
Availability in small to large frame guns (not all S & W)
Can be loaded light (factory) to heavy (see Elmer, above)
Reputation for accuracy, especially with proper throat and bore dimensions
Has the number "4" in front, therefore we Americans like it
Hope this is helpful.