Let me spit some cold and hard facts to all of you; the story doesn't really care whether Nagant was a well-written character, or whether or not she was powerful. The story wants to build tension and stakes, and it has rightfully done so.
You wanna argue that the way she died was anti-climatic? Fine, I'm not stopping you. But this would also be ignoring the very cause behind her death, and honestly? That cause is extremely twisted and ****** up when you think about it. So there shouldn't be any excuses going around saying that "this was an extremely disappointing way for her to die." Correction; this was a very ****** up way to die. End of story.
Could this have been done better? Probably, but when you look back in retrospect on a lot of manga's and their chapters, many things could have been done better. This is a pointless argument to make. Her debut, as short as it was, was beautifully done on Horikoshi's part, and now it's possibly being wrapped up to further the development of the cast.
This is wrong. Everyone's not praising Bakugou because he did the bare minimum of teamwork, they're praising Bakugou because he gave fluid instructions to his teammates and perfectly countered Setsuna's team flawlessly. That's more than just simple teamwork. For someone of Bakugou's caliber? It's unexpected for him to work this well in a team-focused environment, which could also be a reason he's being praised.