Voluntary indentured servitude is the act of selling oneself into temporary slavery in exchange for a service or good. As far as transactions go it's simple business. I'm for it.
INvoluntary indentured servitude is being forced/forcing someone into temporary slavery. Most of America used to do this up until the 90s with workers lines for prisoners convicted of certain crimes. They would pave roads, cut grass, raise livestock, etc. to repay their dept to society, which is also something I can get behind.
I understand that some would be concerned for the safety of the indentured servants in question, however you must remember that even during the days of slave in America most masters did not beat their slaves (although this has been dramatized in recent years), and this was during an era where subjects such as torture were far more acceptable than they are now. The servants would either be compensated and doing so of their own free will, or they would be doing so to compensate for something they had done.
And of course regulations would likely be put in place to restrict what can and cannot be done to a servant. Overall I'm perfectly fine with this idea.