Earlier quoted context omitted.
Writing a demand letter that leans in favor of your client's interests is not only okay, it is the standard course of action for a civil dispute. https://www.law.cornell.edu/wex/demand_letter
Perhaps they shouldn't. If we lived in a world where lawyers were more cautions about what they attached there name to out of concern for losing their license we would probably be better off. Less bullying by corporations with lots of money etc. No problems with demand letters for legitimate issues that are well supported by evidence though.
That's already the case. Lawyers can be disbarred for filing frivolous lawsuits.