Hell seems designed to punish disobedience and perceived immorality. Would you agree that acting in a certain manner simply because you fear punishment is cowardly and an invalid motivator?

The coward is the individual who, out of fear, refuses to do what is right.

A coward is NOT someone who, out of fear, CHOOSES to do what is right. That man is not being cowardly -- rather, he is being prudent and sensible.

Fear is an excellent and perfectly valid motivator toward good works. God uses it frequently and He instructs us, at times, to do likewise.

The Book of Proverbs is filled with examples of the wisdom of a proper fear of God...

Proverbs 9:10
The fear of the LORD is the beginning of wisdom, And the knowledge of the Holy One is understanding.

Also take a look at Proverbs 3:7, 10:27, and 14:27. We see the same message throughout scripture, such as in Isaiah 8:13, Micah 6:9, Acts 9:31 and 13:16, 2 Corinthians 5:11 and Revelation 15:4.

We are also taught that instilling a fear of punishment into our children is a Godly and therefore healthy way to raise them.

Proverbs 23:13-14
Do not hold back discipline from the child, Although you strike him with the rod, he will not die. You shall strike him with the rod And rescue his soul from Sheol.

Further, God has ordained governments and enabled them to create laws that we are to be subject to (Romans 13:1). He has further given those governments authority to punish us if we disobey their laws. The intent of these punishments is to cause fear for those who are evil (Romans 13:3-4).

Of course, if it ever comes down to a choice between fearing the government or fearing God, the Bible informs us of who we should fear more, and therefore who we should obey. In the words of Christ, "I say to you, My friends, do not be afraid of those who kill the body and after that have no more that they can do. But I will warn you whom to fear: fear the One who, after He has killed, has authority to cast into hell; yes, I tell you, fear Him!" (Luke 12:4-5).

It would be cowardly to choose to NOT worship the living God simply because people may condemn you for following Him.

It is wise and prudent to worship the living God out of fear of the eternal condemnation we all justly deserve.