There are several things at play here in regards to why things have settled out this way. But the gap between 2-10 in the state is not as large as some of you would like to believe.
The WIAC schools are really good because the coaching is top notch. All the head coaches and their respective staffs are die hard track nerds, and they care a lot about the kids they coach. They turn a lot of mediocre guys into respectable athletes. Their passion, knowledge, and personal skills win over mild DI talent level guys. The WIAC culture is also boosted by a lot of high school coaches who went to those schools, so they advise their athletes to either go to wisco or go to their alma mater. Plus if you decide to go DIII you are there because you truly love the sport. No incentive from scholarships, big trips to meets, free swag. Kids either run seriously (to the best of their ability) or they just move on.
The non-UW DI schools are so mediocre for the exact opposite reason. The coaching at those schools is so minimal or just plain ineffective. They have scholarships, bigger budgets, better competition, and still they barely compete with the WIAC. The coaching staffs at the DI's are laughable, almost all of them are full of guys who don't even have a USATF Level I, which by the way is extremely easy to attain. The athletes don't respond well at these programs because they don't have to earn anything and because their coaches either don't care or they are idiots.
At Marquette and Milwaukee specifically, the staffs are full of clowns. If both of those programs joined the WIAC tomorrow and had to play by the same rules (no budget/travel/gear/scholarships) they would lose whatever talent they have left and fill it with 4:35 milers (although in some cases they already do this).
All that said, the gap between the DI and DIII programs is actually decently even at the moment (lax, uwec, marq, parkside, uwm, oshkosh and other wiacs)
Bottom line
WIAC schools-- are pretty near maxed out because they have superior coaching (both from actual knowledge, and better personal skills) but the lack of scholarships and budget prevents them from getting top notch talent.
Milwaukee-- Coaching staff is extremely lazy and embarrassingly uneducated in the sport. This program has potential to have the most upside in the future. That future depends on two things: Getting Pete Corfeld to retire, and bring in a real coach.
Marquette-- Coaching staff has no passion or drive to get better, they get some talent but never develop it into anything. Mike Nelson is not going to leave anytime soon, so the program will continue to suffer for another 10+ years.
Parkside-- Keep an eye on this program, they have a really good young coach who has already shown he can turn his talent into results. However, Kenosha is a hole and they don't have a strong history to recruit on...
Anyone else have any additional insights?