Why do these restrictions still apply today?
These restrictions still apply because God has never given the human race permission to do any of these things. They remain anathema to Him today, just as they were when James instructed Gentiles to abstain from pollutions of idols, fornication, things strangled, and blood.
Les explains that James, as moderator, decided not to trouble Gentiles turned to God, but to put strings on it: they were to abstain from pollutions of idols, fornication, things strangled, and blood. Les notes it is amazing these things were repeated, yet not surprising because they still hold true today. God has never given the human race permission to do any of these things; they are still anathema to Him. Les points out that verse 21 gives the reason.
But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood.