CyberCubed touches on an interesting point.
This is now a 10+ year series. The producers of this show cannot realistically expect to retain all their fans over such a long period. Sure, there will be the few dedicated zealots like some of us, who started watching at 6 years old and are still watching at 17, but for the most part this series recycles fans. And whatever else the anime is, it is still a money-making venture, so it must work mainly to appeal to its current fanbase at any given point in its tenure.
To those who have watched from the beginning, we get to see that Ash is slowly working his way into being a better trainer, measured by his placing in each League, but newcomers only see how well he's doing at present. Credit to the anime goes for being able to manage the old and new fans at the same time, but they have to do it by making Ash lose continuously, albeit each time losing nearer his goal.
But gosh... 10 years and he's just halfway there. League tournaments are not infinite, so he can't pull this not-quite-there routine off indefinitely. He could plateau, as with getting the same placement in Johto and Hoenn, but for him to place lower would be a backstep (though it would only insult fans older than that current generation), so it's unlikely that would happen. But how long do they plan to drag this out? Like I said above, this is a money-making business, meaning its intent is to continue pulling in revenue as long as humanly possible. Which will win out - the conclusion of a long-running story's final goal achieved or the juggernaut income builder this decades-old franchise proves to be?
I can just imagine being forty years old and hearing through some incedental grapevine the words, "Hey, Ash won the League!" And then a certain door to the past will feel as though it finally rumbles closed...
I started writing this post with a point in mind, but seem to have lost it. So I suppose the idea is simply that it's much more pleasant to watch whatever the show provides than worry about what or when Ash wins. *shrug*