Hangout power users not always goes through the Google+ user interface to launch hangouts. Instead they just bookmark a link and launch hangouts right from there (of course you must be signed in).
Unfortunately Google recently has converted the launcher link hangouts.google.com into a hangout information page. That left users wonder how to quickly launch hangouts now?
No worries, +chew chew who manages hangout engineering has recently offered https://plus.google.com/hangouts/_ as an immediate alternative for launching hangouts.
Please create a shortcut or bookmark this link and start using it for launching hangouts. Google+ team will announce if any new link changes are available. Enjoy!.