Okay, so here's the thing with this... Pokemon's cast of characters aren't normally these deeply emotional attached characters. For one, they can't die (in the game) so we aren't invested as much. This was said about the cast of SM and XY. I recall hearing bad things about the characters in say DP when they first came out. BW and BW2 were only viewed as "good games," once everyone got past all the new Pokemon.

It's also to be noted, that knowing everything works out for these characters can make you care less about them. Like, if Lille's mom would have died at the end? We would all care a whole lot more about her. If Hau had gone under some needed character development then we might have liked him more.

That's the thing though, Pokemon games have never promised us this. What character development did Blue have? Just because some rivals/characters did have character development such as Silver or N doesn't mean all of them do, and it doesn't mean those characters will be looked at as favorites. Who acually says "Silver is my favorite rival!".