I like Johnson, but no HC experience is a concern. He'll be the hot name and rightfully so, but it was only a few years ago when Eric Bienamy was the hot name who never got the chance to be a HC and look what he has done without Mahomes or Andy Reid. He's coaching in college now.
People are taking the offensive vs. defensive coach talk too seriously. The right coach needs to be the right fit for the existing team and have a vision for how he wants to build the team in the future to his strengths.
For all those saying the Bears need an offensive coaching to develop Williams, that's certainly a valid point, but that doesn't guarantee success. Since 2000 the Super Bowl winner has had the #1 or #2 offense only twice, while the #1 or #2 defense has won the Super Bowl 9 times in that same span.
I don't know much about Johnson or his persona, but initial reports are that he's wanting way more power than a first time head coach should have. I think Vrabel would he the best fit and would get the most out of the players. Carroll has had success, but is too old, regardless of how much energy he has he wouldn't be a long term solution.