For years I carried what backpackers consider a "traditional" backpack. A traditional pack weighed right around 30 - 40 pounds for a man, around 25 pounds for a women. We did most of our big trail trips using traditional packs since the equipment options were few in those days.
The Triple Crown trails (AT, PCT, CDT) take several months to hike. You start in the spring, finish in the fall. It doesn't matter if you hike with ultralight gear or traditional gear, you will need to make adjustments to that gear to accommodate the changes in weather and environment. All thru-hikers will exchange clothes and equipment in towns (most often the post office) along the trail depending on the type of environment they will be going into. What we wore in New Mexico would not be the best selection for going over the mountains in Colorado, Wyoming, Idaho and Montana. Though the basics in your pack remain the same, there are those fluctuations in weight mostly with clothing, water, and food.
The last *short* trip we made with ultralight backpacks took us over a month to complete on the trail. During that time, we ran into scores of other ultralight backpackers who had been on the trail much longer (months).
There are good backpackers and there are terrible backpackers. There are highly experienced backpackers and there are very inexperienced backpackers. There are liberals, conservatives, in-between, slow, fast, fun, miserable, positive, negative, whiners, exhorters, extremists, the smart and not-so-smart. There are successes and failures, equally. Discussing the bad is not nearly as educational as discussing the good. If one wants to intelligently discuss "ultralight versus traditional", he will have to have some experience with both. Asking questions about either is a good way to approach the issue. Making bold statements about something one has little or no experience with shows bad form and most often these people are not teachable (been there, done that, got the t-shirt).
Extremes exist everywhere. So what. I love guns and have been a member of the NRA since the 60's. I am greatly disturbed when I see someone commit a crime with a handgun. I know several groups that will judge all handgun owners based on what some psychopath does with his handgun. We see it almost everyday in the news. Myself, I don't judge all ultralight backpackers in light of what some extreme minimalist does. More so than not, I have witnessed many, many more people who go at backpacking carrying FAR TOO MUCH for the distance they are planning to travel (you know 'em when you see 'em). We don't laugh at these folks or polk fun at them (we been there too!), but we do our best to help them understand what is really needed for their adventure and how best to carry it.
Reading most of the posts here on this thread, I'm guessing most folks don't travel very far by a thru-hikers standards. In that case, take the kitchen sink! I do, on the really, really short trips.