Because no one made a 41 special round.
This is almost exactly on the mark.
Skeeter Skelton, Bill Jordan and Elmer Kieth all got involved in suggesting S&W make a .41 caliber revolver.
However, the original plan was for a cartridge that would launch a 210 gr bullet at about 900 fps - pretty close to modern .40 S&W performance and pretty close to the old .38-40 in a carbine. It's a power level that gets the job done, without being abusive to the shooter.
S&W introduced the .41 Magnum in the adjustable sighted Model 57 and in the fixed sighted Model 58.
Remington introduced the cartridge as the .41 Magnum, rather than the .41 Police that Joran had preferred, as a marketing ploy after the success of the .44 Magnum.
Unfortunately, the Model 57 and Model 58 were indeed fairly popular with outdoorsman who liked magnum loads such as a 210 gr bullet at 1400 fps.
That was excessive for law enforcement use from a recoil perspective. Worse, many departments felt that even the 210 gr bullet at 900 fps produced too much recoil. Not surprisingly we're seeing the same response to day with departments moving back to 9mm pistols as some of their officers have difficulty qualifying with a .40 S&W.
The Model 58 with a 4" barrel was also considered to be heavy, but as I recall it was still only around 40 oz unloaded - about the same as a 1911 and no one whined about the 1911 being too heavy.