No argument here, but this is also the entire point! Skiing is fun on many levels. But it becomes more fun the better you get at it. Again, I've never met anyone who, after learning to make a better turn, wished he hadn't!
Skiers who primarily use their skis as brakes--very easy for an instructor to see simply by watching a turn or two, particularly observing how those turns begin--can have a ton of fun. They're up in the mountains, after all, getting exercise, enjoying the sunshine and fresh air, playing with their friends, and feeling the sense of accomplishment that comes from conquering new challenges, skiing terrain they haven't skied before, and so on.
But there is more. I see it daily, from students who discover the sensations and sense of control that fundamentally different turns bring. Good turns--the forgotten art that this thread addresses--are exhilarating! Suddenly, the old "turns" that were once "fun" just don't provide the satisfaction, or the thrill. They want more and more, and they never want to go back. There are sensations in turns that simply do not exist in the movements that most skiers make, or the things they call "turns," no matter how advanced.
But--like Degas's painting--if you don't know how to do it, you'll never even know there's any more to it.
One sure sign that a skier could use a lesson is when you fail to find challenge not on the Double Diamond and challenging off-piste runs, but on the "easy" groomed green runs. Green runs lack challenge only for intermediate skiers and hacks. For beginners, and for true experts who seek more than "just getting down the mountain," there is plenty of challenge and fascination even on the "easiest" terrain.
I totally agree with you but I can also see the other side of things. It's easy to want to improve and learn new things when you can ski all season and don't mind giving up a day or two learning new things.
However, learning new technique is frustrating and often involves a retrograde in your performance before you can get past where you were before. For the people who only get a few days a year it's more enjoyable to ski how they ski then to spend their whole vacation frustrated with new technique that seems to make them "worse"