Improvement
Basic assumption: Improvement Is Good. More is preferable to less. I mean, c'mon people; there really isn't much in life that's more fun than learning, than suddenly understanding something you previously didn't. And even beyond that, learning more almost invariably lets you do things better and faster. It opens up new doors for understanding how something gets done, and even lets you discover new somethings you didn't even know existed.
Mo-ti-va-tion!
The problem, then is one of motivation. It's nearly impossible to learn if you're not motivated to do so. And it's nearly impossible to keep from learning if you're motivated to. Every teacher knows that; trying to teach someone who doesn't care is a painful chore, but when you have a student who does, you have to work hard to keep information flowing to them as fast as they're eating it up. And those are the ones who make the whole process of teaching worthwhile.
It's neither fun nor productive to try and shove knowledge down unwilling throats. The real challenge of teaching is getting your students motivated to learn.
Enter the curve
Now, let's apply learning curves to this. To make use of a Unix system, you have to climb a steep curve. There's a fair bit of initial work and knowledge you have to put in to aquire just a basic level of proficiency in it. It takes some investment of time to get to the point that you can do more than just stare at it. So, by the time somebody has a working knowledge of Unix, they've put a fair bit of effort into it.
By contrast, the shallow learning curve of Windows allows very quick and easy integration. A person can gain a working knowledge of Windows in an hour. It doesn't require any studying, or much questioning. For all practical purposes, it's almost indistinguishable from no investment at all.
Behavioral psychology rears its ugly head
All amateur psychologists, gather 'round. I pose to you a simple query. Given these two users, one of whom has invested the time and effort to gain a knowledge of Unix, and one of whom has invested the nothing to gain a knowledge of Windows, which one is going to have the motivation and the inclination to push forward and continue learning?
And that's the clincher, isn't it? One person is left with the impression that "I don't need to learn nothin', the computer does it for me", and thus has no reason to believe that learning more will improve their experience. After all, they didn't need to learn anything to get this far. And beyond the impression of the utility of learning, there's the question of investment; he has nothing invested in the project of using the computer, so he has that much less motivation to invest more. You're always less commited to improving something you achieved in passing, than something you've already put effort into.
Our Unix person, otherwise, naturally gets the impression that "I can do X, Y, and Z with what I've already learned; I wonder what I'll be able to do with the next batch of stuff I learn?" Now this is the "Good Student" attitude! They already recognize that learning has given them a tangible reward, and they have a natural excitement (more pronounced in some than others, of course) for what gem will next be revealed to them. Additionally, as mentioned above, they've already invested in this event, which makes them that much more inclined to invest more.
And, very soon, they catch on to the fact that "using computers" isn't something you learn and do; it's something you learn and learn more. It's not an item, it's a field. There are practically uncountable levels of facility you can have in it. Trying to say that there are only two categories, those of "Can" and "Can't" is one of the greatest disservices you can do to the realm of computer usage.
The more you learn, the more you realize there is to be learned. For those who have learned practically nothing, they often don't even realize that there IS more to be learned, to say nothing of having any inclination to learn it.
To the next level
Now, let's move on to an examination of the effects of learning curves on the systems.