For me a "wrapped dll" is used when you use a dll where you don't have the code and you want more control. For example in win2k/XP, you can't stop the Crtl+Alt+Supp. The system treat this before anything so if you make a keylog you can't stop this but you can replace the dll which do the security and treat the key with your dll. His job is just looking the args if it's not Ctrl+Alt+Supp then call the "real dll".

I hope this help (and be clear).