I think the difference is that what you are calling "conservative offense" is actually "incompetent offense".
Last in the B1G in yards/game, 2nd to last in points/game, last in passing, bottom third in rushing. The 2022 season was worse. That's not conservative, it's horrible offensive coaching. The incompetence, coupled with nepotism is what draws the criticism.
The Barry Alvarez and Paul Chryst Wisconsin teams were "conservative". That was a choice to be dominant in the run game, use play action and bootleg in the passing game to control the clock and grind teams into submission. These Iowa teams are trying to be good offensively, even if it's not with intent on scoring 30+/game, but they are incompetent.