> It's not a threat of a "more severe sentence", it's a threat of a default sentence The "default" is updated when you learn about plea bargain... You are now

> It's not a threat of a "more severe sentence", it's a threat of a default sentence The "default" is updated when you learn about plea bargain... You are now comparing options relative to plea sentence. If the best option "walk free" is uncertain even if you're not guilty (what if the other guy has a better lawyer or something) then plea sentence is the best certain option.