Regarding your first paragraph: the primary components of a football offense, an army, or any fighting force are people and methods. We are in quite good shape on the people side, it's been getting better but has long been above average at the OL as you indicate. The problem has been and is, clearly on the method side. Without even watching, but just using deductive reasoning, if the OL people have at least been ok, but the results(especially running) have annually been in the bottom half of the conference, then the problem must be with the methods. And it is. Lack of misdirection, poor play design and blocking schemes, poor pass route trees, bad clock management, poor risk/reward decisions.......
An OL coaching candidate will not have a problem with the people side. But he knows that as OL coach, he can't control methods, although those methods can either facilitate his task or make it next to impossible. The best he can hope for is to have a listener who is open to his suggestions. Doubtful that he would see that as a likely possibility with KF and "family".
Regarding your second paragraph: legendary ?, Hof F ?, reputation in coaching community?
Most college HCs aren't fools and privately see the program for what it is: great developer of players,
a little less than average in P5 recruiting, high level of defense on a national scale, and an offense that has been badly underperforming for years, even within it's own conference, with insufficient action to change it's trajectory.
That hardly meets the qualifications for legendary or H of F.
They would support that contention quite easily by pointing out that only once in the last 10 years
has the team even seriously contended for the championship of it's own weak division.