I don't see it as controversial. Yamada Senssei's views are well known but he always makes it plain that they are his views and not an official USAF stance.
My own opinion is that he is frustrated by the reliance on titles; promotions and ambitions of a lot of Aikidoka who seek to gain prestige by them.
I disagree with hin, however, since every organization from the smallest dojo to the Aikikai needs a structure and titles, rank etc. provide this. That is not to say they should be sought for their own sake, but considered for what they are - a useful tool.
Well, it works pretty well, for children, not so much so for adults, IMO. You have to balance the usefullness of this and any other tool against the rather substantial negatives of the system.
Of course, there are plenty of groups that have gotten by for hundreds of years with very little in the way of ranks, so I don't think that it's a given that Jigoro Kano's system, which is only a few years old, relatively, is the only feasible method of organization.