I've ragged on theological liberals for being to Gospel-centric, where focusing on the four Gospels gives then the opportunity to major in grace and ignore both the Old Testament law and Pauline discipleship. I've also been uncomfortable with some theological conservatives (the late, great Michael Spencer for one- I owe him an obit) who feel a sermon has been wasted if a direct reference to Jesus isn't part of the package.
However, it is that Gospel, that a guy named Jesus, God incarnate, came, preached, died for our sins at Golgotha and rose again. Without that, there isn't nearly as compelling a reason to crack the book open. Paul's commentaries have little clout unless you buy the idea that the Messiah that the four Gospels talk about hit Paul over the head with a 2-by-4 on the way to Damascus.
If understanding God is our goal in order to follow and worship Him better, there seems no better spot to start than on the best articles on His incarnate self. If you drop back 10 yards and put the canon definitions on the back burner, you're still left with the four Gospels as our best documentation on what Jesus did while He was with us. It's a skimpy biography for the most important person in history and beyond, but they are well-documented by contemporaries as legitimate chronicles.
Thus, that is a key starting point in my understanding of the Bible; if we want to know what God is like, the Gospels are a key part of that and should be ignored at our peril.