President Obama's plan, announced Friday, to make community college free for promising students, will be seen by some as a game-changer.

As the president noted in his speech, his proposal -- “America’s College Promise” -- is based on Gov. Bill Haslam's Tennessee Promise program, which offers free tuition to students attending two years of community or technical college. While the president’s plan will certainly make community college accessible to many more students, it is also far from clear that such students will benefit.

At present, nearly 60 percent of community college students do not finish their degrees within 6 years of enrolling.

Consider that, at present, graduation rates for students at community colleges are dismal: around 25 percent for students who do not transfer, the lowest 6-year completion rate in U.S. higher-education. (For the roughly one-fifth of community college enrollees who do eventually transfer to a four year college, the graduation rate, at 62 percent, is far better.)

At present, nearly 60 percent of community college students do not finish their degrees within 6 years of enrolling.

Despite the president’s best intentions -- absent serious reform -- pressuring community colleges to improve outcomes, graduation rates have no reason to rise. And by directing more students to community colleges without demanding higher standards—students will become eligible for two free years of tuition if they maintain merely a 2.5 GPA, hardly stellar in this age of rampant grade inflation—the president's plan might, perversely, worsen graduation rates.

To that end, the president insists that participating schools will need to "adopt promising and evidence-based institutional reforms to improve student outcomes." Indeed, the success of his proposal depends on demanding a greater degree of accountability from community colleges, though it's not exactly clear what such reforms might entail.

A better idea: rather than force schools to follow top-down commands, reward successful schools instead by making eligibility for federal funding contingent on satisfactory completion and employment outcomes. (Alternatively, steer students receiving funding to two-year technical schools, which boast better graduation rates than general-education community colleges.)

Regardless of how it all turns out, the president's proposal will not solve the larger problems facing American higher education, namely, ever-rising college tuition and student debt. Further, despite his pledge to “[help] every American afford a higher education,” large federal subsidies for community colleges might exacerbate such problems.

Flush with new funding, community colleges might, for instance, be tempted to imitate their 4-year peers and increase spending on administrators, frivolous capital projects, and other extravagant amenities. Tuition hikes would, in turn, invariably follow—the brunt of which would be borne by students ineligible for the new federal subsidies.

Yet under the Obama plan, even many newly subsidized students would likely not escape unscathed. At present, nearly 60 percent of community college students do not finish their degrees within 6 years of enrolling. As such, it’s likely that newly subsidized students—many of whom will not graduate over the course of their two year subsidies—would inevitably need to worry about tuition increases as well.

As more American families and students question the value of a college degree, it’s essential—as the president rightly does—to emphasize that college graduates outperform their non-degree holding peers on a wide range of outcomes. Accordingly, policymakers would be wise to find ways to maximize the value of students’ tuition dollars.

Alas, simply enabling more students to attend college, without creating the right incentives to ensure better outcomes, is not one of them.

Judah Bellin researches higher-education policy at the Manhattan Institute and is associate editor of the Manhattan Institute's Minding the Campus website.