Concept: Ease of learning as the key to long-term fun?

It is often said that games should be easy to learn so that new players can "jump right into" the action. Recently I've been through a couple of discussions that refined my ideas on what makes a game enjoyable after the tutorial-mode phase of "these are the basic concepts." I think learning plays a substantial role, and I think this may be an excellent test for defining a "good" game. I haven't found a failure case yet. The general idea that I've whittled it down to is that, in an ideal game, each progressive step in mastering the game should feel as accessable as the previous one. Players should be able to evaluate their progress easily. Advancement should help to uncover new aspects of play, and ideally should offer some sense of accomplishment. My rationale is this: Players are not frustrated by chance failure(unless it's of the kind where you lose some game record of your progress like stats or plot advancement, or when failure is built into specific mechanics). What *does* make them frustrated is repeated failure and being incapable of understanding why, or how to overcome the specific challenge. And people can become addicted to a game they otherwise hate because they always think advancement is just around the corner. In FPS games, there is a division between obvious failure(in straight deathmatch) and non-obvious failure(the realistic/semi-realistic games). When I think back to games like Counter-Strike, it now seems like everyone playing is gambling - hoping for the big round. Few people have any idea of how to advance their skills, so they let probability do the work for them. Sooner or later, the big round comes, and there's satisfaction, but it's only temporary. Games like Quake don't allow this because the skill division is always entirely clear; no(or infrequent) teamplay, no randomized shooting, and a complete focus on comparing abilities. As a result fewer people play the traditional games now because it's painfully obvious just good a 'good' player is, and the learning process feels particularly arduous since it requires going out and getting beaten over and over. In any RPG the advancement is almost entirely through stats and plot; this makes them very accessable to anyone who is willing to put in the time, leaving only the caveats of grind. In Bemani(music games), the progression from the most simple songs to the most complex ones and the process of getting perfect scores is always straightfoward; reading abilities, dexterity, and timing are all tested in as direct and obvious a fashion as possible. The difficulty and grading systems always leave enough room(up to the designed limits) so that advancement is "just around the corner." For most people, it really is; the component skills are practiced 100% of the time the game is played, with very little downtime, so even small, irregular play sessions can add up. Anecdotally, many players of these games claim not to have started out with great interest, but found it so addicting that their interest became second-nature. The reason why our tastes in gaming all vary, if this concept is taken as fact, must be because of our differing learning abilities. Only a minority of people will ever be great at any one game, but people are turned off not by their maximum potential, but the marginal difficulty of advancement. Whether or not the game is actually easy isn't really the issue; it's the illusion of accomplishment that's the key. And the most accessable games will offer this hope to a broad range of players. Also, this implies that story and scripting aren't really factors to help or hurt replayability unless they are constraining the game's challenge. If by the end of the first game the player is playing to finish and not out of addiction to the gameplay, they aren't likely to play again unless they can easily return to some area they liked or make a different choice.