First of all, comparing a .45 ACP to a Volkswagen is all kinds of wrong...
Second, it's completely safe to shoot .45 Super/.450 SMC out of a USP, it's kind of a selling point of the gun, that they're overbuilt, and if you've ever heald a full-size USP, much less an Expert, Elite, or especially an Mk23, you'd know immediately that they could take it. The things are built like tanks and have a service record to prove it.
Lastly, because modifying things to make the stronger, faster, and better is an incredibly fun as well as rewarding experience, so even those who are modifying old 1911s to run hotter ammo have their reasons.
Youse gun, youse $$$. Have at it. In the end the turtle won the race........Not the hare.