I agree, there is nothing wrong with plastic. When I hear about frames developing stress cracks, stretching or some other problem it usually involves some sort of aluminum alloy. I prefer steel if weight is not an issue and plastic if it is.

Nothing wrong with aluminum in a properly designed gun but I only own two with aluminum components, a 22 compact with an aluminum slide and an AR.

If someone likes the way metal looks and feels that is 100% subjective and there is no wrong answer. Personally, I think wooden grips look out of place and ugly on stainless steel revolvers and despite people trying to convince me I am wrong nobody has ever succeeded. It's nice S&W provides options.