It completely depends on one's typical ride. If you're climbing 10% grades all day in lycra, then 5 lbs makes an enormous difference. If, on the other hand, you're carrying a 10 lbs lock and 40 lbs of stuff in your panniers, then, yeah, the weight of the bike won't matter that much. In the latter case a heavier bike may actually be better.
As much as everyone obsesses over weight, it's not the only difference between a $500 bike an a $5000. The more expensive components are also going to have more-difficult-to-quantify benefits like fit and finish (i.e., look prettier). The higher-end components also work better: shifting will be much more consistent, bearings will roll more freely, brakes won't require as much force, etc.
This is analogous to a car magazine complaining about how a particular model has a "mushy gearbox." You can still drive it, but the experience isn't as nice.
As much as everyone obsesses over weight, it's not the only difference between a $500 bike an a $5000. The more expensive components are also going to have more-difficult-to-quantify benefits like fit and finish (i.e., look prettier). The higher-end components also work better: shifting will be much more consistent, bearings will roll more freely, brakes won't require as much force, etc.
This is analogous to a car magazine complaining about how a particular model has a "mushy gearbox." You can still drive it, but the experience isn't as nice.