No one is hiring an option coach. While it would be neat, Georgia Tech was the trial balloon and it didn't work.
Bowled nine times in 11 years, won one of three conference titles since 1952, tied for fourth-best winning percentage in program history. Paul Johnson did pretty good, maybe uncharitably just fine. Illinois has bowled five times since 2002.
What would've counted as "working"?
And the better question is this, what different route should they take that we can tell has "worked" most of the time? Any normal route they go, more spread, great recruiter, defensive coach, offensive coach, CEO coach, I can point to legions of spots where that failed terribly. The option is a risk. There are pluses and minuses. It's bad for recruiting. Option teams have issues fielding good defenses (that might be a question of where the offense is installed, but that's worth exploring). But it tends to yield effective offenses and lets you be different.
And if the answer is, the guy at Ga. Tech had a better winning percentage than all but one Illinois coach since 1941, but that didn't work, then it ain't much of a reason. Shoot, if it doesn't work out, that's the same outcome as every Illinois coach since 1991.