No point in spending the political capital, especially when there is zero chance of an actual conviction in the Senate.
Obama is a lame duck.
You do what is right, because it is the right thing to do.
Nothing else matters.
And he is not a lame duck.
He is malignant cancer.
He would be out of office long before we ever got any testimony out of him.
He needs to be tried and convicted in a criminal court after he leaves office.
I see no problem in compiling a list of infractions large and small.