There are a few factors behind a lot of that. Tracy was the producers' attempt at making the show
more suitable for international audiences that wasn't really needed. The reason later seasons might feel so different is because there is so much filler and much less seems to happen in each episode. The First season was made when Gold and silver were already in development, So the first season could (read: had to) move at a fast pace. Afterwards, they had to stretch each Reigonal arc to last the entire generation of games. 8 gyms and the pokemon league in a single year? kind of entertaining. 3 years? slow and boring. 45 years? Mind numbingly dull.
Why does ash keep giving up his Pokemon? Because there's now way to have 10 episodes based around Noctowl if he's still using Pidgeot. Why bother with Cyndaquil if he still has Charizard? As for why Ash is still around
at all, it's another case of the status quo ruling all. all those kids watching every Saturday morning, holding on to their Pikachu dolls without even the slightest interest in the games would be pretty put off if ash left and they got stuck with some beret wearing loser and his electric squirrel.
But nobody cares about any of this, right?