I started out with 1911/Sig226/CZ75.
What I appreciated about polymer pistols (mainly Glocks and lately M&Ps) was that after 500-1000+ round range practice session, there was a lot less shock/trauma to my hands/arms as much of the shock/vibration was dissipated by the polymer frames. With metal framed pistols, your hands/arms/bones/joints absorb all the shock/vibration.
With metal framed pistols shooting full power 40S&W/45ACP loads, you feel the hard "THUMP" when the pistol fires. Newer polymer pistol models like Gen3/Gen4 Glocks, M&Ps, XDs also have stiffer recoil springs so there is less slide slapping of the frame. With metal framed pistols, this adds more stress to the wrists.
For a new, YOUNGER shooter who hasn't developed sufficient hand/wrist/arm strength to apply proper two hand grip on a pistol will find the lighter and often softer recoiling polymer pistols more attractive and may conclude that polymer pistols must be better. I have helped many new shooters select a pistol for SD/HD purposes and let them shoot a wide assortment of pistols. They tend to get better groupings with lighter Glock triggers that does not need to be "broken in" over most other pistols - the ease of getting smaller accurate shot groups first time speaks volumes to them and gives them confidence. Also, we now have a new generation of younger buyers who grew up watching movies and TV shows that glorified Glocks. Put yourself in their shoes, "If the police carry Glocks, they must be good?" Many idolize law enforcement and the military. When they shoot the Glock 17 and Beretta 92FS side-by-side, there is no comparison for a new shooter, Glock 17 wins hands down mostly due to lighter weight, smaller size and cheaper price tag. Yes, they don't make that much money either, for now.
Most will agree that Glock's introduction has raised the bar for the semi-auto pistol manufacturing world-wide and the competition among the manufacturers have produced better and better pistols for us shooters. I think most major pistol manufacturers are spending their R&D money on polymer framed pistols and not on metal framed pistols due to customer demand and lower manufacturing costs (if you only knew what the cost to produce a Glock is
).
I do not believe "metal" framed pistols are dead. It's just that lower priced polymer framed pistols that shoot well outsell in overwhelming numbers because of word-of-mouth recommendations like, "Trust me, buy a Glock/M&P/XD and you won't be sorry". How can you argue with that? I have made that comment many times when someone asked they can only afford to buy one pistol for SD/HD. When you are comparing prices, new buyers also say, "And they cost less too?" - it becomes a no-brainer.
I would be very happy to see metal pistols make a comeback though.