Why the commandments are good
1) Commandment keeping indicates a submission to God's authority and reverence to His word.
2) The commandments are the written representation of the character of God.
3) Keeping commandments is all about faith (Romans 14v23 with 1 John 3v4)
4) Keeping commandments is all about faith working through love towards God. (Romans 13v10)
5) God keeps the commandments. (Psalm 25v8)
6) The commandments make us depend on God for the Spirit (Psalm 119v10)
7) The law brings conviction of sin that leads to conversion. (Psalm 19v7a)
8) The psalmist enjoyed the commandments (Psalm 119v47)
9) Commandments make the heart rejoice (Psalm 19v8a)
10) Keeping the commandments makes society a good place to be (Psalm 33v12)
Other things about the commandments:
1) The law can never make us acceptable before God as it becomes 'weak through the flesh' (Romans 8v3). Therefore it can't be viewed as a list to earn God's pleasure.
2) The Christian should keep the law to glorify God by faith (working through love) to express the pleasure of God's perfection. Christ fulfilled the law and claimed that it was still applicable (Matt 5v18).
3) Christ's perfect obedience to the law (His righteousness) has been transferred to every Christian by faith (Rom 5v1 with 2 Cor 5v21).
4) The implications of 3) give that every Christian has a righteousness which exceeds the righteousness of the Scribes and the Pharisees. This means that every Christian is entitled to the Kingdom of Heaven (Matt 5v20) :-)
Note: The words 'commandment' or 'law' always refers to the moral law (the 10 commandments) in this post