Many of these well-known apps on the App Store are ostensibly just a skin over an API. Are they not just pushing and pulling text, images, and videos to and from a service and presenting it? Why have they grown to such huge sizes? None of these appear to have significant media assets:
Facebook: 59.3MB
LinkedIn: 51.3MB
Pinterest: 37.8MB
Google+: 35.3MB
Yelp: 30.0MB
Sleep Cycle: 25.8MB
Twitter: 18.9MB
Clear: 13.7MB
Speedtest: 13.9MB
For contrast, here are a couple apps proving a decent amount of functionality can be contained in sensible bundle sizes:
McTube: 6.6MB
Hacker News by Ashish Gandi: 405KB
Safari.app's application bundle on OSX is 28MB.
I will say one thing though - I do wonder if some of it is driven by multi-platform tools that are stuffing their own internals in there. Then you throw it all into one big package instead of splitting it up for different platforms. I've seen some internal app builder tools become quite large before. Especially by firms that think they need to roll their own version of everything, which AFAIK is standard operating procedure for a lot of those you mentioned.