The hypothetical science fiction technology to download knowledge directly into the brain gives you knowledge without discipline. That could be a problem. If knowledge is power and discipline is responsibility, then it creates people with great power and no responsibility, otherwise known as supervillains. So even if you shortcut the fancy book learnin', you need minds trained in general mental discipline, ethics and critical thinking first. You might be able to put some of that into the download, but for other things there's no substitute but actual, real-time training.
Mokalus of Borg
PS - In general, the time taken to learn something makes its own discipline.
PPS - Which becomes more of a problem when that time approaches zero.