I find application of the word "should" to be of questionable value, especially when it's applied by one person to another person's actions.
We all have a set of rules that we live by, and while some of these overlap for a lot of people (don't hurt people just for fun, for example), I have rules that don't apply to you, and you have rules that don't apply to the next person in line.
The word "should" carries a hint of moral obligation, and can suggest that one believes that his or her moral and social values are also held by others.
Just my non-authoritative opinion.