Of course it is. Is the nav light required by the regs? Yes. Are you aware of this? Yes. Are you knowingly making a decision to disregard the regs, because you feel it is not important? Yes.
Seems pretty blatant to me. The FAA has prosecuted for a lot less than this. Practically speaking, I see where you are coming from.
This is how I see it:
Lets say you're taking off from a rural Utah airport that is uncontrolled, and it's 3 AM, so there is no one around. Your destination is another uncontrolled rural airport in the middle of nowhere. You have functioning strobes, a working beacon, and the other two nav lights are working. There is a very slim chance that you will even see another aircraft for the duration of this flight, even if you did, you have a lot of experience flying in that area, so a mid air collision is very slim. That is not a blatant disregard for the regulations.
On the other hand, lets say you have no strobes, the beacon is very weak, and both red and green nav lights are burnt out. You will be flying from Philadelphia to New York. The controllers at both airports are known for their snitchieness, and at New York, the Feds are said to be in town. You have very little experience flying at night. This situation I'd call a blatant disregard for regulations.
Here another situation: Lets say you're flying an air ambulance flight from Phoenix to Denver. After you get to cruise, you kick on the auto pilot. You pull out the AFM to read something so you don't fall asleep. You notice that one of the pages have been ripped out. Its one of the table of contents pages. According to the letter of the law, if that AFM is not complete, the plane is not airworthy. What do you do? Land at a rural airport in the middle of nowhere as soon as possible? You are flying a non-airworthy plane, are you not? Is it not illegal to continue a flight after you have discovered the plane to be not airworthy?