Not much of a point to miss. Chesterton likes philosophy. He doesn’t like theology. lots of points. one is that a such an offhanded dismissal suggests the hamster wheel in the mind might need a little oil. For Chesterton seems to indicate, of Aquinas, that philosophy develops theology. And in that, Luther was something of a Luddite.
Philosophy does not develop theology. Wikipedia defines philosphy as such:
Philosophy is the study of general and fundamental problems concerning matters such as existence, knowledge, values, reason, mind, and language. It is distinguished from other ways of addressing fundamental questions (such as mysticism, myth, or the arts) by its critical, generally systematic approach and its reliance on rational argument. The word "philosophy" comes from the Greek φιλοσοφία (philosophia), which literally means "love of wisdom".
If one is to believe the scriptures to be the inspired word of God, then the Bible contains the answers to the fundamental problems of man. You won't find it in reason or philosophy. You will find it in the scriptures.
In Aquinas' Summa Theologica he states:
And thus God, by causing in things the good of the order of the universe, consequently and as it were by accident, causes the corruptions of things, according to 1 Samuel 2:6: "The Lord killeth and maketh alive." But when we read that "God hath not made death" (Wisdom 1:13), the sense is that God does not will death for its own sake. Nevertheless the order of justice belongs to the order of the universe; and this requires that penalty should be dealt out to sinners. And so God is the author of the evil which is penalty, but not of the evil which is fault, by reason of what is said above.
Do you believe that God is the author of the "evil which is penalty"?
It is remarkable that Aquinas could hold a whole discourse about "evil" yet never discuss sin. In fact, rarely does he quote scripture. Had he spent a little more time in the scriptures he would have discovered that we are children of evil.
Gen 8:21 And when the LORD smelled the pleasing aroma, the LORD said in his heart, "I will never again curse the ground because of man, for the intention of man's heart is evil from his youth. Neither will I ever again strike down every living creature as I have done.
According to Aquinas' Summa Theologica man is capable of distinguishing between good and evil. This is not what the scriptures teaches. Luther was right to suggest this type of philosophy should be burned.