High school kids that have the talent to get drafted high in the draft aren't going to college for their education.
Why does everyone think the job of an NBA player is so hard intellectually? Many blue-collar workers in this country didn't attend college, work hard for a living and are decent citizens. Where is the outcry for them not getting a higher degree?
If they are of age (18) with a high school diploma, I say they should be eligible. If teams and the league are concerned with the level of play they shouldn't draft them. At the very least they shouldn't draft them in the first round, where contracts are guaranteed.
If teams would draft on actual talent rather than potential none of this would be an issue.