See and avoid is important because anything that helps you avoid another aircraft is a good thing.
However, see and avoid is a myth, however much we have been taught otherwise, and however much we wish other wise.
Here are some sobering facts that I referred to in another thread:
From the CAA
“The principal means of avoiding collisions in uncontrolled airspace is “see and avoid”. Available evidence suggests that the effectiveness of “see and avoid” is questionable when used in isolation (i.e. not in conjunction with a radar service), implying an increased risk of failure to detect a loss of separation.”
From the professional pilots association
“It is publications like the FAA's Advisory Circular on collision avoidance that help perpetuate the idea that all you have to do is pay attention, look out the windshield, and you won't have a midair collision. Rather, the FAA should be telling pilots how dangerous the see-and-avoid concept really is as a means of separating aircraft.”
Why did thet reach those conclusions?
Well at typical GA speeds between 90 and 180 mph, after the time to react, you have between 15 and 30 seconds to see an aircraft that will hit you. So in that time you have to be looking in the right place, spot a target on the screen that is not moving, and see the target when it is at least three miles away.
In short most likely you will see the targets that arent going to hit you, and hopefully you will see many of the slower moving and turning targets, but (excuse the phraseolgy) you are very unlikely to see the aircraft that is on a collision course with you if you are both travelling in straight lines.
What saves us most of the time is the big sky.
That doesnt mean dont see and avoid, and that doesnt mean dont keep a very good look out, but it does mean you will have a more realistic appreciation of the risks, and I guess it means that on an IFR day when there is inevitably a lot less traffic around you are probably far safer than on a really busy VFR Sunday afternoon in Summer haze.
Still IMHO doesnt excuse the pilot declaring himself VFR if he was not.