I think the problem here is that, in this country, we're not really familiar with inquisitorial proceedings. At the hearing, Johnson wasn't a defendant being prosecuted, he was just another witness. The Committee weren't trying to prove his guilt, they were simply trying to get to the truth. They asked tough questions, but that's their job. It was quite abrasive, but that's because Johnson is well known as an unreliable witness, who conflates and obfuscates, as easily as most people breathe.
But still, this issue about not being able to cross-examine witnesses nags at me. As much as I despise Johnson, my desire for fairness overrides that. And being a sucker for legal dramas, the adversarial system is pretty much hard wired into my brain.