I stand by the saying that polymer handguns have no soul (before anyone blows a gasket, it's a figure of speech not to be taken literally). It's like comparing classic cars of yesteryear to the mostly lightweight fiber glass production cars of today. Yes, the cars of today are lighter, better on gas, etc, but the substantial feel and experience of driving an old school production car is far and above that of product cars of today. If both type of cars were still being manufactured today and pricing was generally in the same realm, yes, modern cars will make more since on paper for everyday use and abuse, but my pride and joy and what I would enjoy driving the most would be the old school classic.
The premise in the OP is correct even if some try and down play it. Metal frame guns have more of an heirloom status, they hold and/or go up in value over polymer guns, they arguably look better, they usually are built with more robust internals, they have a more substantial feeling vs feeling like a lightweight toy, they feel like they are higher quality, and there's a pride of ownership aura about them.
Metal frame Kahrs, Berettas, CZs, Walthers, HKs, Sigs, S&Ws, 1911s, revolvers, Brownings, etc are valued, collected, and mean more to most gun owners than their polymer counterparts - period! "Sentimental" might not be the correct word, but metal frame gun elicit more feelings vs plastic. If all things were equal price and availability wise, most would feel more of a sense of loss if their 1911, Beretta 92, Sig 226/229, CZ 75, and the like were stolen or loss vs a Beretta APX, Glock, P320, M&P, CZ P10c, etc. Guns are tools for self defense and recreational shooting just like cars are just machines to get you from point A to B, but that does not take away from the fact that some tools and machines are valued and elicit more emotions, feelings, and/or pride of ownership than others.