Guns that stand the test of time are often there due to a lack of any concerns over their poor performance. Once used in a critical situation or with enough incidents, then things show themselves to be what they really are, and new decisions often come out from it.
The 1911 stayed in the racks for nearly 70 years simply because the Army didn't need anything better to do what a sidearm does best in that hierarchal organization - assign status to it's wearer in their duties. Not that it's a bad gun, but a single stack single action as a battle weapon fell behind the power curve when Browning started working on the Hi Power. Double stack double actions are now the standard in military use and it's been transferred to police duty, too.
The .38 revolver was another gun left in the holster for decades of use - replaced by the Glock as being far superior. In either case, would it be better to return to them for official duty?
In some cases yes, largely, no. The passage of time is really needed to get humans to catch up on their thinking to adopt new standards of performance. Keeping the same old guns for long periods of time into second and third generations just means nobody has decided to raise the bar. It's not a justification in and of itself that the old guns were superior. It's an testimony nobody wanted anything better.
We used rotary dial land line telephones for decades, too. Stood the test of time, or just all we bothered to put up with? I seem to see cell phones going thru generations of improvement in the last twenty years, with broadcast protocols changing twice.
Sometimes what we put up with is due to our fair weather standards. We keep it around because we don't push the product to the edge or force it into life threatening use. Like, wearing cotton denim blue jeans in freezing rain five miles from your spike camp in the Rockies. Good ol blue jeans have stood the test of time, too, but maybe you could make a better decision.
The FBI recently decided to go 9mm for their next fleet of issue weapons, and it's due to better ammo and the concept the older guns were becoming worn in service and problematic. Maybe we can pick up some of their discards for our use, like the many S&W 5903's that sold off a few years back. But those old guns aren't necessarily all that - government institutions make committee decisions about their priorities and balance the advantages and disadvantages to come out with their choice. Like, the Army with the quad rail handguard on the M4. Ok for them, not the best idea for the civilian shooter on the range or hunting. In fact, more bad than good considering the wide variety of better handguards around.
Don't put too much credence in someone's "official" recommendation - there is a lot of lobbying and partisanship in the hallways where those decisions are made, same as another agency being told to make M855 illegal. You have to consider the source and it's motivations.
