There are documents and witnesses that would greatly increase what the public knows about the Trump administration’s extra-legal foreign policy: who, when, what, why, and for the benefit of whom.
Polls show that most Americans (including a substantial percentage of Republican voters) want to know that information. All Americans need to know what past votes have resulted in, and how it has conflicted with what their Congress authorized. The deserve to know what has been done in their name, and with their taxes. Almost all of the needed witnesses were paid with our money, and the documents were created on keyboards and printers and paper we paid for, and they are stored in files and servers that we also pay for. The evidence belongs to us, not to Trump.
This needs to be said a lot more often and loudly. Somewhat more often within the limited and judicial context of the trial. Elsewhere, it needs be presented persuasively and often. Outside and inside the trial, Trump is trying to win both the impeachment and re-election by de-legitimizing his opposition. A vigorous defense of its legitimacy is vital. More elected officials and commentators need to use this as a strong opening argument. Everyone opposing the abuses of the Trump/republican regime should include it somewhere in their content, even in discussions that start out with legal, national security or other aspects.
A politician who promised and still claims the “most transparent administration ever” has created the exact opposite. Members of Congress (and pundits) who enable or ignore this do not deserve their jobs.
The same applies to media and pundits who ignore or deny that the people want, deserve, and need the facts, the truth, the evidence.