Trezor's older models (Trezor One and Trezor T) have an unfixable seed extraction vulnerability on a hardware level. That's why the company created the SD card protection feature. It's meant to mitigate the mentioned issue and prevent knowledgeable individuals from extracting your PIN and/or seed. What you have done is you have built a big wall around your house, making your home inaccessible and much harder to reach. That wall serves as extra security if you are using a Model T. But the Safe 3 and Safe 5 models don't need the SD protect feature because of the presence of secure elements. Those secure elements may present other attack vectors, though.