ZUN likes to make cute characters total asses, like Nitori.
And people like to accuse ZUN of running out of ideas whenever new characters are revealed. People claimed Nue was a rip off of Flandre (Which makes no sense.), people did the same thing with Junko, claiming her rivalry with Chang'e is a retread of Mokou and Kaguya's rivalry (Also weird, because it's completely one sided, to my knowledge Chang'e hasn't ever killed Junko.), i'm sure people said the same thing with Kagerou, and probably many other characters. It's really annoying because technically ZUN's been doing this since the beginning of the windows era, i mean, Meiling is literally just Orange.
Seeing her arcs and profiles in HM and ULiL, yeah, Nitori's a pretty unfortunate example since I liked her MoF/SA design and personality a lot.
Now that you mention it though, I'm still fairly new to Touhou compared to many veterans here, but I've heard that accusations towards ZUN upon the revelation of new characters happened pretty much with every game. I've even seen somewhere that people even were initially quite toxic against the SA cast at its full release, now we've all seen in the recent popularity polls where especially Koishi and Satori have gotten to. As with DDC and LoLK, the only two major games of which I've witnessed the release up-close, I for myself didn't really saw any of the accusations except for that the musical characters in DDC are rather forgettable and that Junko VS Chang'e has ties to Mokou VS Kaguya, of which the latter comparison actually makes a tad bit sense since one side is (still) a Lunarian, while the other side is not (anymore). Other than this and that each arc involved a casualty, they're not really
that similar. I literally don't see any similarities between Flandre and Nue aside from both having extraordinary designs for their wings and being EX bosses, Koishi would actually be more similar to Flandre since both are EX bosses and the younger sisters of mistresses that appeared in the respective main games. I guess that's the Touhou fandom for y'all, even though I'm not that sort of person who likes to accuse everything. People fortunately mostly settle down as time passes.
Let's hope that ZUN is actually being nice with the new cast :V