Mr Katz took over the BBC's current affairs show last summer, after the programme got into hot water following its aborted investigation into Jimmy Savile and false accusations against Lord McAlpine.
Newsnight has since hit the headlines thanks to Jeremy Paxman's interviews with Russell Brand and former Co-op Bank chairman Paul Flowers and Emily Maitlis "interviewing" Cookie Monster.
But Mr Katz said : "Kirsty dancing to Thriller was one of those memorable moments, the kind of thing that makes the audience say, 'I must stay with this programme to see what happens'.
"Any suggestion of dumbing down is painfully preposterous. Newsnight is more serious than at any time in its recent past."
Paxman was criticised for being too soft when he interviewed Mr Flowers, who stepped down as the bank's chairman amid claims of illegal drug use and inappropriate expenses payments.
Mr Katz said: "One of Jeremy's strengths is he can do different types of interview - oppositional or emotionally intelligent. There is a discussion to be had about interviewing - heat versus light.
"It's often possible to get more interesting insights without going in with your arms swinging, but the audience does seem to crave the drama of the bout. You get damned either way."
Asked about the presenter's on-screen sneering, he said: "Most of that is hammy, part of his shtick, and people love him for that, just as they love him for asking the same question 15 times or raising his eyebrow with such scepticism it seems the interviewee will dissolve in the chair."