Ever read any of Paul's writings? How about Acts 15?
Acts 15:28 For it seemed good to the Holy Ghost, and to us, to lay upon you no greater burden than these necessary things; 29 That ye abstain from meats offered to idols, and from blood, and from things strangled, and from fornication: from which if ye keep yourselves, ye shall do well. Fare ye well.
Why do Catholics now try to demand more "necessary things"?
You mean like this?
1 Cor 11:23 For I received from the Lord that which I also delivered to you, that the Lord Jesus in the night in which He was betrayed took bread; 24 and when He had given thanks, He broke it and said, “This is My body, which is for you; do this in remembrance of Me.” 25 In the same way He took the cup also after supper, saying, “This cup is the new covenant in My blood; do this, as often as you drink it, in remembrance of Me.” 26 For as often as you eat this bread and drink the cup, you proclaim the Lord’s death until He comes.It's interesting that St Paul didn't reference the burdens you mentioned but actually delivered them the Supper of the Lord. Maybe you're just reading Acts 15 out of context again?27 Therefore whoever eats the bread or drinks the cup of the Lord in an unworthy manner, shall be guilty of the body and the blood of the Lord.