People who ask this sort of question assume that the cryonics era just comes and goes in a few decades. I find it more likely that cryonics or its successor technologies will become part of mainstream medicine indefinitely. If you have an illness or injury (probably some new kind of pathology we haven't seen yet) that the health care providers in, say, the 22nd Century don't know how to treat, they would put you in some kind of biostasis for attempted revival in, say, the 24th Century, when medicine has advanced enough to know what to do.
So why would people in the 22nd Century want to revive and rejuvenate and transhumanize people from the 21st Century? Well, they might return the favor for their resuscitators in the 24th Century.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.