First of all, any sort of impeachment proceedings in the senate are going to be presided over Justice Roberts (as described out in the constitution), so the ability of Moscow Mitch to influence the proceedings will be limited.
Secondly, why exactly are you assuming that even if they had a 'robust' debate in the Judiciary committee that the republicans wouldn't vote to acquit anyways? The republicans are corrupt. Regardless of whatever evidence is provided, they will not vote to remove Trump. Suggesting that giving more power to the republicans in the name of 'robust debate' might somehow convince them to remove Trump is foolish.
We have seen how the republicans act... holding a pizza party to complain about access to the hearings, when they actually had the ability to actually attend, demands to interview the whistleblower (which would amount to illegal intimidation), having Nunes involved (even though he's got a clear conflict of interest). Trying to allow more 'robust debate' will likely just result in more conspiracy theory nonsense, more grand standing, more bunk from the republican side.