Pell Grant recipients are more likely to have the risk factors that make it less likely to complete college - and the risk factors that make it more likely to receive other forms of welfare, such as Aid to Dependent Children, Food Stamps, WIC, Earned Income Credit, etc.
So, an analysis of their value has to factor in how Pell Grants affect other welfare programs, as well as compare the success rate of Pell Grant recipients to non-recipients.
That said, there should be some restrictions on what types of degrees Pell Grants can be used for. Handing out Pell Grants to students pursuing degrees that will be virtually worthless is as much a disservice to the student as to the taxpayers.
As a few others have mentioned, the colleges may not be as excited by their students' future job prospects as they are about receiving their students' tuition money, so they may not find it in their best interests to funnel students into degree programs where the demand already exceeds supply (simply expanding high demand degree programs isn't always a solution if the pay working in the field is better than the pay teaching college classes).
