There's actually a danger to the incredibly quick character development in the long run. If their arc is done so quickly, what else are you going to give the character to do? If their flaws are gone so quickly, how can you keep the conflict up?
How it pans out depends on how long the series will eventually be, I guess.
I agree. Another danger is that issues will be too self-contained, where each arc has a character or two address a personal issue but also resolve it in the same arc. I'm not too concerned with this being a problem yet, despite only really Todoroki and maaaybe Bakugou carrying their issues in a more longitudinal manner, because it still feels like a lot of characters are still being fleshed out.
How Iida is handled in the upcoming chapters will affect my view of future character development a lot. This definitely needs to be the sort of event that changes him positively but leaves him with issues or trauma, especially with all of Deku's ominous foreshadowing.