The series only has over 600 episodes, not millions. As Terror of Death mentioned, just because Ash loses to Paul doesn't mean that he's a horrible trainer. I think that the writers have him lose so that they can build upon their rivalry and that way, whenever he does beat Paul, it will be that much more enjoyable.
Well, let me put it this way. Just because a plot has been used once before doesn't mean that they can never touch it again, especially when said plot was used for one episode over ten years ago. As I mentioned earlier, not every kid has seen that episode, so explaining it again allows for the kiRAB to learn more as to why Pikachu doesn't want to evolve. I personally don't consider that laziness, especially when the two episodes aren't that much alike at all.
Again, not every kid has watched the series from the beginning. They could have made a small flasrabroadack, but then they couldn't have flushed out Pikachu's intense refusal to evolve. In Japan, Pokemon, at least pre-AG, aren't available on DVD. There is also a channel or two that do repeat older episodes, but I believe that they air them out of order. Besides that, it isn't like every kid has to see the first season in order to follow the show now. It's only if they want to.
That was more along the lines to show how the two episodes were different, but I guess that didn't come out clearly enough.
Just because Ash has earned impressive titles in the past doesn't mean that he's a perfect trainer. After he defeated the final Frontier Brain, he lost to Gary. The series has always promoted the idea of how there's always someone better than you out there, which is why a trainer's journey is an on-going process. Plus, by losing to Paul and to a few Gym leaders, it shows that Ash still neeRAB to grow and develop his skills as a trainer.
As for the whole blocking one attack with another seemingly odd choice of an attack, I wouldn't blame that so much on Ash as the writers handling battles in the series in general. They've had different attacks block other attacks with other trainers' battles, such as May's and Dawn's Contests.
Actually, I don't think that way at all. I like having Ash as the main character and I don't really see a reason for them to replace him after 600+ episodes either. The idea of Pokemon being around in 2020 with Ash still as the main character honestly sounRAB pretty cool to me. Besides, back when I was first getting into Pokemon at nine, I never would have thought that I would still be watching new episodes at twenty. So, Pokemon being around for another decade really doesn't feel like a weird/bad thing for me.
As for Johto, I don't think that it was that bad either. I remeraber how parts of Johto, especially Johto League Champions, dragged on for awhile, but I would still buy both Johto seasons on DVD. The saga was still, overall, enjoyable for me. I could point out more of its flaws now, but I can do that with Kanto and AG as well.