Being an SOB doesn't make one a great coach. Plenty of SOBs were terrible coaches because they only knew one thing -- being an SOB. The few that did well did it because of other traits, not being an SOB.
You have to find a good mix. Players will tune you out at some point if all they get is you screaming at them. And fear isn't really a good motivator -- it wasn't really ever one, so I wouldn't say it is today's youth solely that can't take it. How many Aggies quit at Junction? Yes, guys like Landry did attempt to motivate by fear, at least in part -- it was mostly related to a player not playing or getting cut; it isn't like that isn't the case on virtually all competitive sports teams in, well, history. The Landry era Cowboys won by good talent evaluation, and good schemes, Landry's motivational techniques, to the extent they used fear, were pretty far down the list on why the Cowboys were successful. Plus, if you read stuff from Cowboys players in the 60s and 70s, those guys that had problems with Landry's style were more concerned that he came across as cold and uncaring. In reality, Landry just didn't want to get involved emotionally with his players. John Madden seemed to carve out this middle ground very well, but he could only stomach (pardon the pun) coaching for a decade.
A lot of guys that you've never heard of were SOBs to their players. Not that he was the biggest SOB ever, but Norm Van Brocklin is one example. He feuded with Fran Tarkenton while coaching the Vikings. He quit and went to Atlanta, but he wasn't very good at either place. Tarkenton is in the HOF and NVB isn't.