The U.S. needs to impeach a president (with something that resembles a reasonable cause, of course.) one of the greatest failings of the U.S. democratic system is that the president has never actually been forced out of office. Despite previous impeachments, no president was ever removed from office by the senate, thus rendering impeachment a fairly toothless threat.
For democracy to function it must be established that certain standards are to be adhered to, and that failing to do so will result in removal from office, not just impeachment, which doesn't affect the president directly.
Of course it can be argued that people can vote for or against a person, but ultimately that is a corrective measure that can be far removed from the actual incident, thus allowing the president to inflict further damage on the nation or to sweep any misdeeds under the rug.
Of course all of this hinges on representatives, and by extension voters, supporting a system in which the president is not immune to consequences, and so far there have never been a precedent of the president being held directly responsible for any act.
It can be argued that earlier impeachments have resulted in consequences similar to removal, but the fact that removal from office has never been formally enacted allows people to doubt that it might ever occur. Had any of the previous impeachees been removed from office the parties would have to consider the actual character of their candidates, not just their electability. Because at this point you needn't concern yourself with staying in office, only getting there. It is unlikely that Trump would have gotten a nomination in a world where the republican party would have to consider his past record and whether or not he would commit some impeachable offence based on said acts.