First of all: I don't hate Pewdie. I used to watch his videos. I really liked (and still do) his Amnesia the Dark Descent and Penumbra Overture & Black Plague playthroughs. Because at least to me those first videos of his looked more real; his jokes were more appropriate and his reactions felt more natural.
However, I lost my interest at that point where everything possible had to be turned into a joke. I don't like those characters he's making for example. They feel so forced. Amnesia is supposed to be a horror game, and I was interested seeing players' as natural as possible reactions during playing. That was the thing for me that made watching let's plays fun.
But sadly nowadays many people's attitude towards horror games seems to be turning them into jokes. And if there's absolutely nothing to make fun about, then let's take some vaginas and penises along. Last time I remember finding such jokes amusing was at the age of ten or so. My reaction to those is usually just raising an eyebrow while asking "Really..? Can't come up with anything better?"
Then there's... some of his fans who seem to think "Amnesia = PewDiePie", and assume that if you happen to like Amnesia you must also like Pewdie. Servant grunts have becomes "bros" and every possible object must have some silly name. I can no longer find any decent Amnesia fanart for example. When I try searching those I get just Pewdie, Stephano, Piggy etc.
So. *shrugs* I dunno if I'm just an old fart who's lacking a sense of humor, but anyhows, I haven't found his videos being fun or entertaining for a loong time now. If he will ever go back to the way he used to be, I'll definitely start subbing again.