I think when they were looking for a replacement for Louie Anderson, they wanted someone ENTIRELY different.
Louie was, by some accounts, channeling Richard Dawson. He was also VERY inconsistent. Some shows, he was very funny, other shows, he looked tired and bored, and looked like he wanted to get it overwith. His gravelly voice was also irritating after a while. I had heard that a LOT of editing and pick ups were needed to be done because Louie made many mistakes.
Richard Karn, however, was a much more consistent host. He was very friendly, very likeable. I do think he missed MANY opportunities to respond humorously to rotten answers, but he had his moments. I think that over time, Karn was being a little TOO consistent and each show looked pretty much the same.
John O'Hurley, I feel, is a terrific choice. He has the charm that Dawson conveyed very well on Feud. He's more consistently funny, and I think Family Feud feels a lot like the Family Feud that I watched as a kid.