Really no big b/c there are 3rd party apps (mostly free) with these functions and also better than the Apple apps.
Weather -- Weather Channel and Weather Bug
Stocks -- Bloomberg
Clock -- Alarm Music Clock (.99)
Calculator -- Calculator XL and Jumbo Calculator
Voice Memos -- Sundry Notes (does a lot more than voice memos)
Bottom line: Whatever is missing... there's an app to replace that so no functionality is lost.