Animated specials are just that. Specials. They're not meant to substitute the main show. They tried a series without Ash in it. Pokemon Chronicles. See how well that did? See how we continue to receive new episodes? Wait...
It really does just prove that while other characters are popular and marketable, they are no where near as popular as Ash. No other character has or ever will be as popular as Ash - aside from Pikachu himself, and you can't have one without the other. You can give other characters Pokemon Ash has had, but you can't just make a new protagonist and just give him/her a Pikachu. When that happens you can kiss goodbye to the series. Other Pokemon are also not as popular as Pikachu. Pikachu is an icon the world over. Pikachu is a household name. Someone could have NO IDEA what the other 650+ Pokemon are, but they will recognize Pikachu.
There would essentially be no Pokemon Anime without Ash. It would end up being an entirely different show altogether. And the reason they're not doing it is because most people are happy with how it is right now. People like Ash. That's why Chronicles is dead, and why characters like Brock and Dawn get specials - they don't need more than that. Ash, however, is the plot of the series. The series revolves around him becoming a Pokemon Master, and while it's not repeated as often as it used to be, it is still the focus of the show. Behind every subplot in the series, the main backbone is the plot of Ash achieving his dream.
How many people name their in-game character's Ash? More than you'd think. Ash is named after Satoshi Tajiri, the father of the franchise, the reason we all live and breathe. Ash is the embodiment of the "catch em' all" slogan. Ash was the one doing what we all wished we could when we were little and watching the show.
So what if the new generation has no idea who Misty is? So what? So what if they haven't seen the first season, which is irrelevant anyway, since they continue to market the original show, and even offer episodes online. You can go on the official Pokemon website right now and watch old episodes. And kids today WILL go on the official website, as well as sort themselves into the many online Pokemon Communities, where they will hear about the old shows as well. It will be impossible for them not to know the old show exists.
So really your point is entirely moot right now. Newer fans do know about the oh so holy original trinity. What I'm wondering is why you continue watching a show you only have bad things to say about. Seriously.