Well, AFAIK, the set of people I have interacted with and many others over the forum do not hate Pihu. All of us agree with the fact that the kid is right from its perspective and can empathize with the kid for how it is being manipulated by shagun and how it is ignorant of the biggest truth of her life. So in no way, we can hate Pihu.
The only point is all of us are pissed off with the creatives for making Pihu look devil with her smirks & smiles, her actions to take revenge from Ishita like biting her fingers, spilling oil on her and most importantly the choice of language that the kid uses for Ishita, it is way beyond a kid of 7 years can use, leave alone a parent, any elders. Just to make sure that shagun has to be shown successful in having a hold on Pihu and manipulating her, the makers are crossing limits with the dialogues and actions of the kids. They did the same mistake with Raman and Ruhi as well. This is the sole reason, why many of the viewers are still not able to connect with IshRa as a couple, because IshRa did not have a proper confrontation & Raman never apologized for his abusive words.
People had the same complaints against Ruhi as well, but then were OK with it considering the mental trauma the kid has been through all these years. Now it is Pihu's turn to be made evil and when she goes overboard with her dialogues & actions, I am afraid people might not be able to connect with her, even after she gets to know the truth and bonds with Ishita.
There were only rantings from people, definitely not against RD / Pihu, but against the makers, for giving her crap dialogues just to glorify one character. It is not for Pihu alone, it is for their general mentality to make the kids as pawns for every dirty games played by one nasty character.