I think plumes are an essencial non essenciality. Confusing?
What I mean to say is that plumes are "the bees knees"(I hope I said that right), and are awesome to catalogue figures as important or not. This does not mean, though, they cannot be ranked without them. As I only have four plumes(or four thirs of 2 plume set, as I only have two big ones and two medim ones), only four guys can be ranked (what is more annoyng is that I had 3 visors with holes and somehow I lost them all) with plumes. But I don't need plumes, because they are simply not that important. What is important is that I want plumes (and holed visors), because I think they are cool. We are not the kids mass to know what they like and don't like, may as we may observe or ask one or two, because wanting or not, we end up influencing them into embracing our opinion. In a final analysis, we may have our own independent opinions, but what count's isn't that, it's only what the kid mass like, and unless they say "we want plumes", Lego has no way but to do what economicly is best for them. Even if one plume set costed 2 cents, in 100.000 sets it would be 2000 dollars more they would have to pay.