Am I the only one who feels there is character development? Even if it is minor sometimes, but there has been a good amount.

There has been some development, but the only significant development we've gotten was in Ian, possibly Utchy.
Episodes that seemingly had character development had, by the end of the episode, the character reverting back to their old habits.

What about Souji in his last episode?

Saw it. It was pretty forgettable.

There has been far more character development in this show than Go-Buster had in its entirety.

Hmmmmmmmmmmm, I don't know that person. I'll have to look them up later today to see what they have done.

I'll save you the trouble since you won't find much. He's a relatively new artist. This is the first tokusatsu work he's ever had. If you ask me, he's done a pretty damn good job of it too.