I am confused how you think other arcs had more character development then the Chimer Ant Arc. There are character introductions and character backgrounds but there is hardly any character development besides Gon and Killua in all the other arcs.

I've written several paragraphs on what I feel are character weaknesses at this point. Meruen, Youpi, and Pitou to a lesser extent were all interesting but I found the cast of heroes outside Gon/Killua to be very dull.

I didn't claim other arcs had "more character development", I just had several problems with the Chimera arc:

1) The characters from the other arcs, Yorknew City arc as an example, are more interesting and hold more narrative weight, as they relate to what to that point had been the "main" story arc (Phantom Troupe). As an example, Chrollo's "character development" in Yorknew City serves double narrative purposes: fleshing out his own character motivations as well as the big reveal of the Phantom Troupe's existence, goals, and purpose, which to that point had been a mysterious and malevolent plot point hinted at in earlier arcs.

2) As I stated before, if the Chimera Ant arc has more character development, it helps that it's literally 3x as long as any other arc. Everything about it, from character development (a dozen Gungi playing scenes), to the fights (Youpi fight had like 5 dramatic twists) is composed more of cliff-hangers and "gotcha!" moments than other arcs.

These are standard practices in shounen anime, but the other HxH arcs do a good job of masking the use of this sort of silliness so that it feels more like a natural story progression. It's just excessive, in everything from development to plot to fights. As I've said before, if there is "more character development," it's because it's literally 3x as long as other arcs, and that doesn't strike me as a good thing.