There was an interesting article in the NYT a while back that discusses this and one doctor that says stimulants could curb the effects of poor/under funded schools... found here:
http://www.nytimes.com/2012/10/09/h...d-pills-to-help-in-school.html?pagewanted=all
While I don't necessarily agree with that, I do think that most students would see a performance boost from therapeutic levels of adhd meds though there will be plenty of people that wouldn't like the way those drugs affect them or just wouldn't be able to tolerate stimulants in general.
With that being said what it comes down to are ethics and health concerns. The first being a question of do we allow a group of people to have an advantage in the classroom that wouldn't be available to those that couldn't tolerate stimulants? In addition those that take such meds to overcome a preexisting deficiency would once more be behind the curb because while they could possibly increase their own doses in an attempt to compensate it would inevitably lead to a much higher frequency of the negative effects of such drugs. Over all it could also be the beginning of a very slippery ethical slope where society is then pushing the individual to make economic and academic success a "by any means necessary" rule that is not only encouraged but intrinsically needed to compete. The health concerns aspect seems rather obvious. There are already many studies that show the possibility of long term negative side effects from extended stimulant therapy especially in children i.e. the although yet unconfirmed theory that it can stunt growth in adolescents. I'd also be inclined to believe that wide public use of stimulant medications could turn into a pandemic of addiction similar if not worse than the current opiate problem. In summation while I think a large proportion of the population could see a boost in mental capabilities from stimulant use the negatives that would go with it would far outweigh any potential benefit.