Does it boil down to people naturally being uncomfortable with adapting to change?
I remember in the events leading up to 5.4 people were initially very receptive to the idea of Vol'jin being Warchief. On the one hand, you have people that would like other Horde leaders to have the spotlight and a bit more development, and on the other you have those that prefer the bread & butter Orc leader status quo.
I say give him a chance. He literally JUST became Warchief at the end of this patch..