Let's not forget that when the first WoW expansion came out, Burning Crusade, it got torn apart by a lot of faithful WoW players. They missed the days of vanilla, and didn't like what Blizzard did. Change 40 main raids to 25, and the armor did not look as LOTR-style in BC than in vanilla.
But, at the end of the day, people still enjoyed what BC was after they spent time with it. I think with how fast we get information now, people quickly jump in conclusions and just want to attack something if it is different.
Yeah, no new raid in HoW. However, Trials of Osiris and Prison of Elders might be some pretty cool content instead. We do not know yet.