You have to remember that proton aren't quite a world class manufacturer. They simply don't have the money, the skills nor the demands. Their cars are mainly built for domestic consumption. They are still years behind the Koreans, and even further behind the Japs/Europeans.
Given they started out having bought Mitsubishis old factory, designs, workers etc when Mitsubishi exited Malaysia, there was always going to be a strong linkage between the two. Nothing wrong with a rebadging, your smaller Fords and Holdens are rebadges.
In fact, your Holdens, Fords and Toyotas in Aus would be in the same state as Proton, if not for the likes of their giant parent companies. Whilst I'm not a fan of their cars, you have to respect a little manufacturer of a little country trying to put their mark on the world with what little resources they have.