While I certainly don't think college debt is quite indentured servitude (you certainly can leave work while still in debt), it's worth noting that US bankruptcy laws are specifically not generous with student loan debt. It's very rare to have it forgiven. Worse, if the loans have a cosigner, the debt can continue to harass them, and they'll typically be a family member.

Of course, it's not going to follow for generations, so you're right about the situation being substantially better than indentured servitude. But the metaphor isn't too far off the mark if its context is toned down a bit.