Nope, I feel like this gave her an actual personality, whereas before she was completely one dimensional in a rather cliched manner.
Back when the Poppy rework was being planned there was a thread about what defined Poppy as a character, and iirc the main keywords at the time were determined, noble, strong, she is all of those things now, except she actually sounds less like a pokemon who can only repeat one word, or in this case can only portray one personality trait/emotion.
To each their own of course, so I can understand people not liking new Poppy, or liking old Poppy better, but she does have a very distinct personality now (completely different from Tristana's btw), regardless of personal preference I think its just fact that her personality is much more developed now, she is still tough and determined, but she is also cute and dorky, little awkward and unaware of just how badass she is, all of which I find make her much more endearing than just angrily shouting.
A point could be made of why not just retain her old personality exactly as it was, but I think the problem with that was exemplified in how you said it yourself, she was -all- swagger and bravado, personally I think thats the problem, her personality was to be one dimensional, which fit better in the earlier days of lol, but as lore and characterization has become more expansive it was necessary to have a less one dimensional personality, so retaining a personality that was defined by being one dimensional becomes impossible.
My opinion is definitely biased as I love new Poppy, so take that as you will, I know for a fact I would be upset/disappointed myself if a champion I liked got their personality changed, so its not like I expect to convince anyone, but it is my genuine opinion on her update nonetheless.
) Poppy has nothing to prove. Also her awkwardness is adorable.
