Admitting you are wrong is one of the harder things to do in life. Hard because it sucks to be wrong about something and have to acknowledge it. But also hard because of the psychology of the human ego and mind. Some people lack the capacity go admit they are wrong because their ego has them jaded and certain about their decisions. For others, they may see what they are doing is wrong but are to arrogant, afraid, or proud to admit they are wrong.
I don't know if any of this applies to Brad, Dan, or the front office. This offseason will tell us for sure. As you said, they need to do some soul searching and reevaluate their plan of action as far as roster construction goes. They need to recognize the mistakes they've made in talent evaluation in the draft. They need to recognize how aggressive they've been in trading up and that it hasn't always worked. In some cases, it's been to their detriment. They need to understand that just as you can't build a team entirely through free agency, you can't expect every draft pick to hit either. You're going to have to shore up your roster holes (and even acknowledge where the holes are to begin with) through free agent signings. It doesn't mean you go crazy, blowing money on the marquee talent that's available, but pieces will assuredly have to be added.
If Brad goes out and gives another one of those receipts press conferences again after this subpar ass season, there will be a lot of people who turn on him. They need to eat a big slice of humble pie, be introspective, understand where things went wrong, and admit that to themselves, if nobody else.