Yeah, it was the "MacBook wannabe" that made me say it. It just sounded like someone defending their turf. Sorry if I offended. You do realize that laptops are also called, "Notebook" computers, and the notebook class is the smaller-than-a-regular-laptop class of laptop. This is why Apple named theirs with the book. Instead of "Notebook" they changed it to "Macbook." Surface just did the same thing. Not even something Apple invented in that name.
You are spot on as to why the new "cooling system" is being used. However, you do realize there is a big difference in the cooling capabilities between heat pipes and liquid cooling, right? Most standard heat pipes move air to do the cooling. Liquid cooling, though it still uses pipes, is never technically referred to as heat pipes. Those heat pipes in the xperia are not the same, and though they certainly help a lot with cooling, they do not come close to the cooling capabilities of liquid cooling. I've run heat pipe systems, I've run liquid cooled systems. The liquid cooled systems I've run have run the gamut from water to liquid nitrogen. I've clocked CPUs over 7GHz using extreme methods. I know what it takes. I've been able to clock CPUs using a good quality ethylene glycol cooling system to 5GHz and beyond. Ethylene glycol is the most common liquid cooling used in pre-manufactured, closed-loop sealed systems, because while it cools as well or better than water, it doesn't have as severe of damaging effects of water should it get loose.
Personally, I am one of those excited about the liquid cooling aspect. I think people will need to take better care, though, and not be dropping their phones every day, as it will likely damage more easily.
They didn't go with the Atom chips because they don't provide the proper performance, and they also can't run continuum. The new Skylake-Y processors will be available in early 2016, and this is what has been chosen for the rumored Surface Phone. Much more powerful while being even more energy efficient according to what I've heard about them. Microsoft needed to get out new flagships with the introduction of Windows 10 Mobile to show what it is capable of doing, and the Qualcomm processors were the best available at the time. In 2016, Intel will have the best available.