I don't post regularly but feel need to respond. Phil, I am glad that you are engouraging discussion and asking questions rather than simply drawing conclusions based on what's in the media. But you're missing the point about weight.
If you read "Accidents in North American Mountaineering," which is an annual published summary of all reported accidents, and you scroll down the statistics tables, you'll see that the top reasons for accidents are: (1) slip/fall on rock; (2) slip/fall on ice; (3) falling rock, ice or object; and (4) exceeding abilities. Things like "exposure" and "stranded" are much, much further down on the list. And when you read the actual accidents, (1) and (2) diminish in more experienced climbers. Personally, I think that falling rock and ice are the greatest danger out there, particularly on a route like the one these climbers chose.
When a climber carries more weight, they move more slowly, with less agility, and increased fatigue over the course of the climb, much increasing your chances of (1), (2), or (3) occurring. The longer you are on any route, the more likely you are to be hit by rock/ice fall, and it happens more frequently than being lost. If you pick up any book about mountaineering, you will see how important it is to keep the weight down in order to move quickly and avoid hazards. For all we know, carrying the bivy sack, extra fuel, and food that these guys had may have slowed them down and exposed them to any of these hazards, including the incoming weather. They were smart and wise to be prepared with these items -- I am not in any way questioning their gear choice -- but every time anyone climbs, they make very carefully thought out choices about gear and weight. Both issues are EQUALLY important. Reducing the amount of weight isn't about being lazy, wimpy, careless, or a risk-taking adrenaline junkie. It's about safety -- NOT carrying stuff is like wearing a life jacket. I know that this is very repetitive of what everyone has been saying, but just trying to say it in another way.
Plus, my understanding is that MLU's only work on Mt. Hood, which makes them of limited value as a gear choice -- not to mention that since these climbers were from out of state, they might not have even known about the MLU's on Hood. There are also personal location devices that work elsewhere but that are very expensive ($700-?) and of questionable value as compared to other safety items that climbers carry.
One more pound may not sound like a lot of weight, but it is, and it adds up fast. If someone takes one more pound by carrying an MLU, there usually is a trade off for other safety gear.