Yeah, I feel ya.
Really, if they were being super careful with the wording, (E) would read something more like:
"Allowing business executives to set curricula for management trainees would increase the likelihood of the trainees developing 'action learning' / studying real cases or increase the likelihood that a business school would respond to the needs of business".
No matter what, "business executives" (the 'NEW GUY' in the conclusion)
somehow needs to be explained in our correct answer: how the heck do THEY relate to addressing the problem described?
Notice, though, by your explanation that you kinda made a case for (E). You were saying that maybe the academics already possess the same insights; they're just not willing or choosing to share them. That would work AGAINST the conclusion, in the sense that we could say "You don't need to bring in business execs; you just need to encourage/force your academic teachers to share their valuable insights."
We only need to resort to getting business execs if they bring something new to the table.
But I agree, it doesn't NECESSARILY have to be "unique insight" that they bring ... it could just be "willingness to share that insight".
Don't let the perfect be the enemy of the good ... i.e. despite the fact that many LSAT questions are written in an airtight fashion, don't go nuts if you have to pick a 'best' answer that isn't as rock solid as other correct answers you've seen in the past.