Because as noted far above the .40 S&W is a little hard to hold on to in a minimum sized pistol and in a full sized pistol other cartridges show IMHO clear superiority - a just right pistol might make the .40 S&W the just right cartridge. A local mainly rural (big animals and far away backup) agency issued .40 S&W but had one person who couldn't keep the pistol from moving in the hand during qualifications so the whole department went to 9x19.
In a full sized 1911 my Platonic ideal is a 9x23 and I would choose a full .10mm over a .40 S&W. In a smaller pistol I can handle a .40 S&W assuming a good trigger and other amenities but I can't compensate for deficiencies in the pistol - compared to small improvements in carry customs - nearly so well as I might in 9x19 so no deep affection.
I have a switch barrel pistol originally .40 S&W with a .357 Sig and 9x19 conversion barrel. The .40 does twist, the .357 Sig is loud, the 9x19 is Goldilocks with far more available premium ammunition.
I have given thought to putting together a .40 S&W pistol to suit adding a long slide and maybe threaded barrel but the only way to get the 5"+ .40 S&W barrel I want (to my knowledge; I miss Storm Lake) is from Barsto where you get what you pay for but you do pay for it. I was actually happy to hear that my last Barsto order would be delayed a day (after some weeks) when the company told me shipping would be delayed one day from promise because Mr. Stone had been called away and their policy is nothing ships until he has at least given it one last look.
