I just rewatched all of Kai and except for the Saiyan arc and to a lesser extent the Namek arc I couldn't disagree with you more.
The Saiyan arc was excellent, imo.>Lots of character development all across the board.>Vegeta never reveals he is a Saiyan prince or anything, just says he's a Saiyan elite warrior and that Kakarot is a lower class warrior.>Vegeta totally overpowered Goku with Goku only able to temporarily close the gap with a Kaioken so high it burns out his body. Vegeta face tanks everything thrown at him including a genki dama. Several fighters make contributions to beating Vegeta until he is eventually worn down.>not to mention everything else about the arc
After that everything became huge/cheap jumps in power levels + waiting for Goku.
The Namek arc had a lot of throwaway characters. There were all of Frieza's guys (including some named ones that were presented as imposing before being trivially killed by either Vegeta or Freiza), the guy that trained Vegeta or whatever, Zarbon and Dodoria, the Ginyu Force, Nail, Guru, other Namekians, etc... The only really redeeming part of the whole arc is Vegeta and Piccolo's character development and the way Goku's fight played out.
After this it was all honestly kind of terrible. Lots of throwaway characters and plots. The Buu arc especially had a lot of things happening but none of it was really meaningful. All of the stuff with the tournament, babidi's warriors, fusion, fucking everything about he kaioshin (lol Z Sword will make you stronk Gohan, lol ultimate power Gohan,...), etc.. was all ultimately meaningless in the end.
In Super, Revival of F starts right off with SS Blue and we don't see any more of that shitty power level jump dynamic. Moreover the story centers on both Goku and Vegeta so there's no more need for "waiting for Goku" arcs and "weaker characters are relevant until the bad guy transforms" scenes.