Im not sure if PCs run cooler per se, but what Im sure is that the "cooling industry" has avanced a lot in the last 10 years.
You have access to pretty quiet fans even at high speed and way better at moving air at high preasure, AIO liquid cooling is a common thing now, and theres more.
Heatpipes are a common thing even in really cheap coolers like the snowman (~17 bucks, shipped included, on aliexpress for a cooler that have the same performance, if not a bit better than an Hyper 212 EVO).
And yes, smaller fabrication nodes allows to get better eficiency and more performance, you don't always need more speed (and voltage and heat) to get better results. And this not only apply to PC CPUs, this benefit console, smartphones cpus too.
Then again all the hardware in the world is not enough if the software can't keep the track.
Not soo long ago the only way to get good performance while performing a heavy demanding task was more voltage, more heat and higher frecuency. Today, with software slowly turning into the use of threads, frecuency is becoming the second part on a two man show.
Anyways, thats my 2 cents.
Cheers