Why is it not considered to be Holy Spirit inspired, and included in the current cannon of scripture?

In Colossians 4:16 Paul instructs the Laodiceian letter to be read to the Colossian church, and vice-versa in Laodiceans? Yet Colossians is considered cannon, and Laodiceans is not?

Interesting?

Wonder if Laodiceans 1:13 offends too much? I love it personally.

Laodiceans 1:13 And for the rest, dearly beloved, rejoice in Christ, and beware of them that are filthy in lucre.