On the one hand, he has a point. There is a stark difference between the feel of raiding back in the days of vanilla, The Burning Crusade, and now. There's a stark difference in numbers, which any graph can illustrate. More and more people can complete raids now from one degree or another, which leaves people barreling through content at light speed and doesn't really give that same feeling that raiding had in years past.
On the other, is changing the difficulty in WoW really the way to accomplish that goal? I don't think so.