I'm of the belief that Iowa isn't going to land the next Anthony Davis, who's now the best big man in the NBA and then pair him with 5 additional NBA picks. In that instance, yes, you can build around a big man but that's not reality.
Frank Kaminsky was the college player of the year for Wisconsin. The other Kentucky team you mentioned, along with Gonzaga, and Florida teams all had NBA guards on their team. Also, that Florida team was 13 years ago (and had 8 guys play in the NBA), basketball has changed drastically since then...
Basically you proved my point by referencing teams with dominant big men, and how they have to play alongside 5-8 NBA players, or be NPOY and play with only a few NBA players, or have played basketball 13 years ago... on a Florida team that had 8 guys play in the NBA.
It's a guards game, and it's why Deandre Ayton (7 footer and #1 pick in this years NBA draft) and Arizona couldn't get out of the first round against a Nevada team lead by two guards. Iowa is much more likely to win and be successful playing 3-4 talented guards at a time than signing 5-8 NBA players, which is apparently what's needed to win if your best player is a big man.