Why did the apostle Paul mention the blessed hope to the Thessalonian church in each chapter of the first letter?

1Thessalonians 1:10 And to wait for his Son from heaven, whom he raised from the dead, even Jesus, which delivered us from the wrath to come.

1Thessalonians 2:19 For what is our hope, or joy, or crown of rejoicing? Are not even ye in the presence of our Lord Jesus Christ at his coming?

1Thessalonians 3:13 To the end he may stablish your hearts unblameable in holiness before God, even our Father, at the coming of our Lord Jesus Christ with all his saints.

1Thessalonians 4:16 For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first:

  17 Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.

1Thessalonians 5:23 And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.

Was it because they needed to be grounded in the doctrine of the blessed hope?

Or was it because they needed encouragement, and reminding them of the blessed hope did exactly that?