Why do people dislike Nexon?

I mean without them Global MapleStory would not be this big, or even not exist.

That is a possibility, but it is far more likely that the rights of MS would be sold off to a 3rd party for GMS, and it could be better or worse or maybe no different.

Anyway, most people just get frustrated because Nexon is incompetent and with every patch their incompetence sticks out like a sore thumb. Not to mention a lot of us are pretty pissed over some wrongful pomegranate they've done (like removing the elemental weapon bonuses).