Prosecutors have the ability to not file cases at all. They also have the ability to offer diversion programs, wherein accused criminals can voluntarily agree to community-based sanctions/supervision in exchange for their cases not being filed. These do exist in some jurisdictions today, but tend to be offered to a very small percentage of defendants.
In short: if they really cared about ruining lives, they’d stop trying so hard to ruin lives (in all but the most serious cases). Changing the Miranda warning may be a very small step forward, but getting prosecutors on board is the only way to make a real difference.