First of all, it is not a FBI investigation. It is a Special Counsel, under the jurisdiction of the Dept. of Justice. Special Counsels are supposed to be assigned a specific task, with evidence of a crime committed, and given authority to investigate, and prosecute that crime within those guidlines. Where was the evidence of a crime? Mueller has been given no such guidlines, which gives him authority to go wherever he wishes. Maybe we should do tihs with every newly elected President,, just to make sure no crimes have been committed. Be careful what you wish for.
Secondly, the vast majority of those in the FBI and intelligence organizations are dedicated, honest individuals. The problem occurs at the top. The people who run these organizations are political appointees, These are the people that can be weaponized against political opponents. We saw this with the IRS. They can also protect their political allies. We saw this with the Clinton email scandel.
We are soon going to see the results of the Inspector General's investigation. I consider him to be impartial;. That should give us a good idea where we stand.
I like your points hamster, just a small point. The IRS is not a government agency. It is run by the Fed, which is a private bank masquerading as a government agency.