Well one person's band-aid is another's significant fix, and only the data will tell.
EDIT: Below is wrong, but keeping it for posterity:
Note that the desktop Magic Keyboards that employ the butterfly mechanism do not seem to have the same key sticking issues as those on MacBooks, so it's likely they felt the fundamental design of the mechanism was fine but that it did need an additional silicone barrier for the lower-travel MacBook variant.
EDIT: Below is wrong, but keeping it for posterity:
Note that the desktop Magic Keyboards that employ the butterfly mechanism do not seem to have the same key sticking issues as those on MacBooks, so it's likely they felt the fundamental design of the mechanism was fine but that it did need an additional silicone barrier for the lower-travel MacBook variant.