Many debts are collateralized, and many are not. Pointing at some common collateralized debts doesn't really have bearing on the argument.
I agree that the government shouldn't be loaning money for college, but I also don't think the government should be loaning money for housing, nor loaning money to banks at ridiculously low rates to bid up the everything bubble - listed in increasing order of importance.
But OP asked what we can concretely do right now, to address the problem that has already been created. Stopping student loans cold turkey isn't going to make colleges magically downsize their bloated layers of administrators and lower their tuition - it's just raging at what has already occurred. Just like how raising interest rates a little bit didn't unroll the screwed up housing market, but rather just caused it to lock up and remain in the inflated state. So the first stab at a practical middle of the road approach is to end the poorly thought out legislative subsidy of non-dischargeability, and start letting the already-created financial situations be resolved through the standard processes. Bonus points if some of the money can be clawed back from the colleges that received it, but the basic dynamic has to be defined before that can happen.
From the individual perspective, going through bankruptcy isn't instantaneous and has effects that last a significant amount of time for someone who just graduated from college. Courts do look at things like ability to generate income. The option is only going to be practical for those with little hope of actually benefiting from their degree.