Yeah, maybe it seems rather repetitive that Brock, Ash and TR have been taken from Anime series to Anime series constantly with traces of changes in the cast. But, sometimes repetition is a good thing.
I agree that Ash is really not the incompetent, rash and very...mild-minded little kid we saw 11 years ago. He has grown 6 years, to the age of 16, by the Diamond and Pearl Saga. He really has grown more mature (in the balance-minded and simple ways, not like relationship wise...PFFT!) than he was before.
I also agree with the fact that he has formulated and vitalized some pretty unique and elaborate plans to configure a sound strategy to defeat the opponent. Very interesting, in fact, that Ash has grown into this, when it seemed before that the anime would only stretch a year and a half...Where Ash would probably die in the end or some crap...I don't know.
But, anyway, going back to the seemingly impatient sounding repetition of the 4th Anime Series, Black and White (And yes, that is the fourth, because Johto and the Orange Islands were all one anime...or was it Kanto and the Orange Islands, then Johto?) is bringing back Ash and Team Rocket. So what? We have grown to like Ash, and he will probably be even more developed at 18 (which is about the age he should be, because he's been on the DP journey for two years *yes, they stated this IN THE ANIME! In that episode that didn't air in U.S.*). So, why should we not like the anime because they've brought back old characters? Other anime that have been dried to the bone, like Dragonball Z, have kept old characters for however long they've been running (OMG, KILL THAT ANIME NOW) and they haven't been thrown aside! (Yeah, people still like it...T_T)
So, all in all, I have kept with the anime because they HAVE HAD character development and overall plotline recreatinons. I probably won't stop watching the anime until they are in their 7th Generation (Yeah, it'll come -_-)