I'm prepping a session on doing Bible applications in talks for a preaching training day I am speaking at on Saturday. Here is a snippet:

Principle: the application is the whole point of doing most messages. That isn’t to say that you can’t preach a message that is just presenting God to the eyes of people’s hearts so that they are helped or blown away by him without any contemporary stuff for their life this week, of course you can. In that case them getting staggered by God is the application.

No passage of scripture was written just to provide knowledge about God. Knowledge is meant to build up love. I see that in Phil 1:9 where Paul says:

this is my prayer for you: that your love may abound more and more in knowledge and depth of insight, so that you may be able to discern what is best and may be pure and blameless until the day of Christ, filled with the fruit of righteousness that comes through Jesus Christ, to the glory and praise of God

That is a great proof text for the purpose of applications. Follow the logic through:

Knowledge and depth of insight aren’t in themselves the goal
They are there so that our love (=Christ-like, cross-centred, God honouring hearts for each other) may increase
Love abounding in knowledge and depth of insight leads to discernment
Love abounding in knowledge leads to pursuit of purity, it leads to us delighting in righteousness in Jesus
When we pure, discerning, filled with the fruit of righteousness then God gets glory and praise

So when we bring applications from the Bible in our messages we are inputting knowledge and depth of insight, in order that love will increase in vitality, in order that discernment, purity and the fruit of righteousness will result, whereby God is honoured.

Applications are for for the glory God.