To be clear, this is not an issue created by lower division teams being able to recruit higher division players. Low and mid-major D1 teams generally don't have the problem of multiple walk-ons, because they're not stuck on recruits that humans are going to beat them for, and are willing to move on to lower caliber D1 recruits when they do get beaten.
What would fix the "problem" of Big 6 programs with multiple walk-ons would be if sim recruiting logic was more intelligent. But as we see in a concurrent topic, there are people essentially complaining that it's too tough. Making sim teams stronger in general doesn't seem like a good way to improve the experience for most users. And anyway, as we see in this topic, it is not universal that people would find sim teams with full rosters of lower caliber recruits more appealing.
Radarpix's point that coaches with mid-major success should be able to take over high baseline teams *before* they crash and burn is exactly right, IMO. There's a way to achieve that without getting into those unintended consequences, and that's by fixing hiring, like they said they were going to do almost a year ago.