If you do some research you will find how "Good" the 38 special was at stopping attackers, in the 1900's, when the United States entered the Philippines American War.
That resulted in improvements to make the "Weak load" better but it never happened ......................
until the Lswc bullet was designed and higher velocities near the 900 fps mark were developed for the "FBI". (1972)
Why it took 3/4's of a century, I have no idea.........
As noted somewhere above the M1892 revolvers used in the unpleasantness in the Philippines fired .38 Long Colt, not .38 Special.
In fact the .38 Special was a response to the not so effective .38 Long Colt. They share the same parent case, the .38 Special is just an 1/8 inch longer but held two more grains of black powder (the smokeless load did not come along until a year later).
The standard load back in the day of black powder and balloon head cases for the .38 Long Colt was a 150 gr bullet on top of 19 grains of FFg generating 770 fps out of a service length barrel. In comparison the .38 Special could develop 850 fps with 21 grains of FFg and a 158 grain bullet.
I think your point is well taken however as it arguable how much more effective the 38 Special was with 8 grains more lead and only 80 fps more velocity. Had the .38 Special been widely used as a service round in the Philippines, I doubt it would have been noticeably more effective.
It did not however take 3/4 of a century to improve the round. In 1930 S&W chambered their .44 Special hand ejector in .38 Special and called it the .38-44 Heavy Duty and a year later a couple companies were producing high pressure ".38-44" and .38 Special High Speed" loads for it. These were on par with modern "+P+" loads and the press surrounding these loads led to the development of the .357 Magnum in 1935 - which could be regarded as yet another improvement on the .38 Special as it was 1/8" longer and operating at 35,000 psi.
The higher than standard pressure .38 Special "law enforcement only" rounds remained popular into the 1970s. The FBI load was developed in 1972 and propelled a 158 gr LCWHP at 1000 fps from a 4" barrel.
SAAMI standardized the ".38 Special +P" specification in 1974 at 20,000 psi max.
The irony here is that the old guys fainting over the original "FBI Load" are not actually getting the load they think they are getting today. Modern commercial "FBI Load" copies are limited to the SAAMI +P pressure and only generate about 900 fps with a 158 gr LSWCHP, as the old FBI load generated closer to 23,000 psi and even with modern powders, 1000 fps is a bit too much to ask for at 20,000 psi. Even more alarming is that the lead used in many of these modern rounds is often significantly harder than the pure lead used in the old FBI Load and the end result is that through the reduction in velocity and harder lead, the bullet won't expand as much as the old FBI Load.