For riders of mid/high-end, med-size, road-bikes, weight is not an issue; all of these bikes weigh what they need to weigh and no more.
Weight is an issue for most smaller riders and entry-level bikes. These usually weigh much more than they need to.
Bikes are sometimes designed all wrong, eg fat tube profiles (as in aluminium frame), but made from steel, or bikes that look like they have suspension, but don't.