I believe that people try to rate or rank the laws of God according to their importance simply because it is human nature to do so. You can see this as a bad habit, but you can also see it as something that makes sense, particularly if you look at the plethora of laws and commandments that can be found in the Old Testament.
On the one hand, this can be seen as a bad habit. It can be seen as cutting corners. We rate the laws because we do not want to try hard enough to obey all of them. We ask, in essence, what is the minimum that we can do to avoid God’s anger. If we look at it in this way, the only way to avoid the bad habit is to give ourselves up more completely to God. We have to truly love God rather than seeing God as someone who must be appeased. Think of it this way: if you love your spouse, you do not do the minimum possible to please them. Doing the minimum possible is reserved for things like classes that you do not care about. Thus, it is important to give ourselves to a deeper relationship with God in order to avoid this bad habit.
However, we can also say that ranking the commandments is a good thing. It shows that we are trying to think and to better understand what God really wants from us. It shows that we are trying to understand what is truly important to God. After all, in Matthew 22, Jesus did not rebuke the Pharisee who asked him which was the greatest law. He did not say that we should abandon the attempt to decide which law is greatest and simply obey all of them equally.