I will try to calmly explain why Bunny Day was hated in the first placed. So back in April 1st 2020 is when Bunny Day originally started. Zipper visits your island and then once you talk to him all the eggs appear all over the island, including Nook Mile islands. The reason why this went out of control was because the spawn rate of the eggs was too high and people were having a hard time getting materials. Keep in mind this was 2 weeks after the game came out in March 20, 2020.
The problem was the Bunny Day messed up several events like the Cherry Blossom event where there were supposed to be DIYS for the Cherry Blossom but the Bunny Day balloons containing the DIYS and Sky eggs were in the way so people had a rough time trying to get the Cherry Blossom DIYS. Not to mention it messed up the whole Fishing Journey when you had a lot of people trying to get fish but all they kept getting was Water eggs instead.
It got so bad that Nintendo had to quickly fix the spawn rate of the eggs, while it did help the Bunny Day event kept on going on longer than it needed to be so it lasted 2 weeks and it finally ended by April 14th 2020. I will say with the new Bunny Day 2021 that its going to last for only 1 week until April 4th, 2021 and the spawn rates of the eggs have been fixed and its more balanced than it was last year. So yeah thats the reason why people hate this event so much. Just trying to give context of what happened because I was one of those players who experienced Bunny Day last year.