Your suggesting Academic Researchers should be consultants for VCs. Sometimes they are! but, just not full time. Usually, they might be on a board of advisors, for a small amount of stock, or maybe as an unofficial advisor.

Now let's cover why not. Simply put: academic research often is only tangentially related, and thus of limited value. The people with the most direct expertise in the area in question, are the ones who are actually doing the technology they're developing, on a day to day basis.