Honestly, the major problem when talking about "weed" is that considering the amazingly wide array of effects, depending on the variety/strain and dosage (from mild relaxant to big high, passing by stone and huge social-bubble alteration), any point based on the generalization of "weed" as a single substance/effect is pretty much moot from the get go.
Most studies and discussions focus on the "high"/"stone", which are already two vastly differing effects, the former may help one work/socialize at low dosage, whereas the latter would generally hinder these activities. Conversely, most people who speak of a positive experience with regular weed consumption refer to milder effects usually based on the genetics of the strain they use and the kind of dosage they apply to themselves. Apples and carrots...
Then there's the matter of whether students or any party-going demographics is better off smoking weed or drinking alcohol, as a matter of public health, when discussing the legalization of these substances. Considering that alcohol is the #1 death factor in the world, not even counting collateral damage (e.g. most violence/abuse done to women and children happen correlatingly to alcohol use; most alcoholics suffer from dire social issues), I, for one, am pretty sure legalizing weed makes sense to a large degree, if we're gonna have other, more dangerous drugs such as alcohol, legal still.
The negative effects of weed, as any drug, are also better contained through education and public health infrastructures rather than morality (subjective) or justice (punitive).