Sure softdrinks can be bad in excess. However the substitutes like fruit juice are no better (no pulp, sometimes more sugar added) and then there are things like tea and coffee to which people add excess sugar (hello Starbucks) to make it palatable. So it is not just softdrinks that are bad but a wide assortment of drinks with excess sugar.
Softdrinks and other calory-dense drinks with zero nutrients are bad in excess in the way that eating pure sugar is bad in excess. It becomes an excess very quickly. A small slice of chocolate cake contains more nutrition than a soda, but is more likely to be considered a dessert or unusual treat.
Part of the problem is that it becomes a standard part of many meals.
Ordering water when you're out (in America) is often viewed as being cheap. I just prefer water, and not bottled water (it's bad for the environment). Even many waiters may treat you worse for ordering water (since they are paid by meal cost / commission).
Our social norms suck.