Terrorists typically attack public places with large crowds because they want to cause the most damage and get the most attention for their cause. Terrorists use explosive devices as one of their most common weapons. Unfortunately, information for making explosive devices is readily available online and in other information sources, and the materials necessary for making the explosives easily are found in many places. Because of the portable nature of explosive devices and the ease with which they may be detonated from remote locations, terrorists rely on this type of weapon frequently.
In 2016, a person could not even go to a political rally without risking their lives. There were violent protests against Trump in Chicago. There is also the problem of police misconduct. The police can just arrest or hurt anyone they want to, even if the person hasn't done anything wrong. It's terrifying for the general public.
No, I don't believe it is too dangerous to go out in public these days. Most people will not face the dangers of going out into big cities or crowded areas. There is still a low likelihood of facing imminent by leaving the house. The best thing to do is to be aware of your surroundings and be safe.
Unless you are going to the South side of Chicago, it is not too dangerous to go out in public. The fact is that crime is down in most areas. Nevertheless, the ubiquitous nature of the news today makes it seem like things have never been worse. They have and it is safe to go out in public.