Dying at low percentages seems to be a common disadvantage to many of the currently perceived as "high tier." However, as has been stated, this is not as much of a con as one would think.
Toon Link, Metaknight, G&W. All three of these characters are very light, but that does not matter. They are often taking their opponents to high percentages and getting KOs without taking nearly as much in return, due to their superior maneuverability and priority. Also, good DI helps these characters live much past their "normal" kill %s.
Also, I'm having trouble finding moves that KO upwards that are easy to hit. Most have little to no range, while others are slow/easily telegraphed, while the others don't have killing power. Examples:
Dedede up tilt - short range
Metaknight up smash - doesn't seem to KO very well
Ike up smash - slow
G&W up smash - powerful, but slow with little range
I could go on, but it just seems more difficult to star KO in Brawl, thus putting a lot of the weight issues in the backseat.