I can't speak for Hong Kong, but as for Macau you need to understand that by the time Portugal was open to even consider relinquishing any part of its territories, it had been almost 10 years since the 1-2-3 riot, that had essentially proved that Macau existed in a peaceful and stable manner only because the PRC permitted it to exist.

By the time 1974 came around, it was clear that the only practical as well as political option when it came to relinquishing control of Macau was the Peoples Republic of China.