Why I cannot use the expose and launchpad from the touch bar?
Something similar happened with me yesterday, I started using a brand new MBP, opened the App Store and my Touch Bar showed me five tabs - Featured, Top Charts, Categories, Purchased, Updates - out of which the first tab was ofcourse, highlighted but when I clicked on any of the other 4 tabs, it just wouldn't make the switch. I even tried shutting the app and restarting but it didn't work.

Few minutes later, I tried again and it worked so maybe it was just a software glitch and Apple probably still needs to fix some bugs. Who knows if it's the same with your Touch Bar? I just tried and my Expose &amp; Launchpad are working fine, so maybe if you give your machine a reboot or just try again after sometime it might work.

Hope this helps.