I think you may have a bit of sampling bias. The only animes that were worth importing to the US, or watching years after their release, are the good ones. If you lived in the US in the 80’s or 90’s and were a boy, most cartoons available to you would be stuff like Captain planet or GI Joe, but there were other cartoons in existence in the US. Character growth was still lacking, but girl’s cartoons followed the assumption that girls wanted TV shows where people talk about their feelings, such as care bears or my little pony.

I think what you’re talking about is the degree of serialization of cartoons. American cartoons mostly had self-contained episodes where everything reverts to the status quo at the end of an episode. This was so the children watching didn’t have to construct a timeline of they had seen the episodes out of order. Well regarded anime, on the other hand, was highly serialized which allowed for character growth across multiple episodes and was less restrictive.