it does often seem that a good/evil conflict is more severe than a lawful/chaotic conflict, but I've never read anything that explicitly says that the lawful/chaotic spectrum is of less significance than the good/evil one. it's fine I guess, but it would mean that the "chaotic" in "chaotic good" means very little.
also I think you're missing degree/magnitude. a mass murderer and a demon might both be chaotic evil, but so can a shoplifter. if a person's general attitude is "f*** the rules, I want this and I'm taking it", that's chaotic evil, even if it's to a much less degree.
Well, I usually find it's better to think of law vs. chaos as a difference between the self and others. In other words a lawful person views the world as a whole and their actions in it within the framework and context of how it will affect others. Conversely a chaotic person is focused on inspanidualism and themselves (even if this is beneficial). So, like, a LG person might set up a homeless shelter because they see it as something that would benefit society on the whole while a CG person might, instead, brew up a pot of stew and take to the streets. A lawful evil person would be interested in setting up a society founded on tyranny and the like while a chaotic evil person wouldn't care one bit about something like that and, instead, focus only on themselves and what pleasures them with little to no regard for others. So, if it helps, you can sort of see law vs. chaos as being 'self vs. other'.
---I am the gentle hand who heals, the happy smile who shields, and the foot that will kick your ***! - White Mage