The preference for the original style of bent (pressed) steel saddles grew up in the age of the <spit> post-CBS Fenders, when the Stratocaster suffered from too many attempts at production cost-cutting.
In the seventies, the Strat bridge/trem assembly was cast in a single piece of Mazak (no separate block) and the saddles were also made of mazak - a casting material made up of a proprietary mix of zinc and aluminium. It was OK for car doors, etc, but not for small parts subject to the stress that Stratocaster bridge saddles are; it tended to crumble in use, at the point where the string crossed it. As well as that, the softer material imparted less snap and twang to the string. It was junk.
Modern Strat bridge pieces have changed and are made of hardened steel. Here are are some awaiting incorporation at the Corona factory.

Today, there probably isn't much difference in tone between the traditional vintage-style saddles and the modern steel block saddles fitted to the American Standard, etc. But the preference for vintage
everything took firm hold during the CBS period.