I agree on the whole...want to change/adjust thermostat via smartphone, you must log into your Google+ account.
on a serious note...The one thing I can see in this acquisition is the idea of cloud/smartphone monitoring systems that was involved and how NEST was able to "adjust & learn" your habits. I can see Google putting this idea/mindset into many other items...maybe Chromecast to understand your viewing habits and be able to say, "hey, it's Monday and this show you normally watch is a repeat, how about watching THIS other show that is similar"
While i "quietly" applaud Google for their ideas in some aspects, I also DESPISE their ultra-intrusive, mainly marketing, approach to things. Sure, Apple could do similar but it seems Google uses it for advertising dollars and Apple just uses it to better things and charge more. Gmail "spies" and sells your info...iCloud doesn't care, just wants you to buy their expensive iOS devices.