Researchers have argued that using stored heuristic cues, people can form opinions that reflect their 'true opinion' or opinions formed with full information. Assuming this form of reasoning is the dominant form of reasoning, it is important to make sure that rich heuristic cues are created and based on sound information, which can then be used later to form internally consistent opinions.
It seems natural that hard news programming, which provides more facts, will help produce richer, more differentiated, heuristic cues. Heuristic cues triggered by hard news have been shown to have a shorter shelf life than ones produced by soft news. By enhancing the shelf life of heuristic cues, soft news is at one level increasing the shelf life of information, but it is doing so by compromising the richness (context, variegated meaning) of information. In short, heuristic cues produced by soft news leave people feeling they know more than they actually do.
On the flip side, one can argue that soft news can in fact be used to inculcate better citizenry. For example, researchers have shown that people who saw progressive drama where women were forced to confront the issue of abortion affected their ability of how they reasoned about the issue and even their stances on public policy.
Soft news has the ability of narrating stories of a variety of groups that we will perhaps never meet in real life and hence it does the important function of sensitizing people to other cultures, sub groups and ideas. Admittedly it doesn't do it well, but when it does, it is likely that it makes people more empathetic.
In all, news needs to do two things to be efficacious: provide information and make that information relevant to people.