You may disagree with censorship, or with what should censored, but most western countries still have censorship laws and media companies need to honour them.
If you disagree with the laws in your country, go out and change them, that's what democracy is all about. But you don't get to change other countries' laws.
Companies like Facebook/Twitter/etc that want to provide international services need to actively honour ALL the laws in the countries that the operate in - those laws may be contradictory, if a movie can be shown in country A but not country B needs then they need to make sure that can't happen or else they are in legal peril - having a portal that a country can use to declare what is illegal in that country is probably a great idea, the alternative is for say Facebook having an employee who spends all their time monitoring the output of a country's censorship office.
Such a portal can be abused, obviously we don't want governments just banning random stuff they don't like, rather than the process of an independent process like NZ's Censor's office, equally we probably don't want to publish the things that are being reported ("look over here, that's where all the child porn is"), I think this is a difficult are - perhaps we should make what's reported here open, but only in categories without giving URLs/details