I don't dislike casuals. They bring life to the game and are as good as everyone else. What I dislike about casuals is that they are Changing the game for their own good and ruining the experience and immersion of the game for everyone else.
I see it like this..."the Casuals" were always the guys doing heroics and struggling to join for the first raid of the game. They lack time so Blizzard implemented LFG LFR queues for everyone anywhere you like and removed to community from the "World". .
Content too hard for you? Were heroics too much difficult for you in Lich King? Ok, we make the content mega easy so there is absolutely no challenge in doing it. Everyone is supposed to do everything easily now for the greater good of...seeing the content
The thing is...we don't want to see the whole game. We want it to be a challenge...a hard challenge that once completed we receive our rare flashy Crown to show off to everyone (I mean the cool looking epics from hard encounters). They were so good because of the unique looks and rarity of it...Now every casual can wear any item because content is all accessible.. And if a casual can do this EVERYONE can do it. There is no feel of reward nowadays.