Why do so many Christians refuse to remember the Sabbath as God commands?

Exodus 20:8-12 KJV Remember the sabbath day, to keep it holy. (9) Six days shalt thou labour, and do all thy work: (10) But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: (11) For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it. (12) Honour thy father and thy mother: that thy days may be long upon the land which the LORD thy God giveth thee.