Dude he was basically a kid that had no idea of what he was doing and who he was eating, what is humanity, what does ethics mean, anything, he was just a sponge learning what the RG taught him... He was a dick, but he didn't know any better.
It's like hating on killua cause he was an assassin, he was raised that way, you don't change until you start getting other reference points. :/
I mean, meruem isn't a saint, but him learning all those things about humanity is just awesome to watch
Meruem was much more intelligent than your average kid.
Its nothing like Killua's situation, we had what lets see, the Hunter Exam, Zoldyck family, heaven's arena, York New, Greed Island and Chimera Ants to show Killua's growth and change. From the time we see Killua he expresses that he doesn't want to kill although he falters in that goal time and again.
Meruem on the other hand changes in around 30ish episodes? He doesn't even really change, he still planned to slaughter the human race. He only planned to let the absolute best of the best in their field like Netero and Komugi live.
Sorry, people are free to appreciate his growth and enjoy him as a character, its just IMO he died a dick. Being close to and caring for one person doesn't make you a good person or someone worthy of sympathy IMO.
This reminds me of GOT where some fans claim that Cersei is a "Good person" because she "loves" her kids, which ignores all of the other horrible shit she did. She certainly didn't extend that motherly love to Sansa when Joffrey was abusing her.
Perhaps if Meruem had more time to develop into a good person and I saw him doing more kind acts like how he did for Welfin and his growing understandings with Pouf and Youpi, I'd have more time for him.
But he died too quick and his newfound self wasn't far enough away from his past misdeeds for me to feel anything for him at the end.