What is the Republican objection to Comey's testimony being totally public? National security stuff?

Why did they agree to transcripts being made public but not the actual footage of a public hearing?

They would’ve preferred not to have a transcript at all, so they could cherry-pick and leak bits and pieces out of context to make Comey and the Mueller investigation look bad.

What Smapti said. Also, Comey is probably going to look like the calm, sane one in that room.

My guess is that one of the Republicans demanded the hearings for his vote on some other issue and the committee is stuck with it. They are trying to downplay the whole exercise because it won’t benefit their message. This is now just a drill they are going through the motions on. A transcript simply makes sure it disappears from the news all the more quickly.