The DVR and fridge may run Linux but that is due to cost rather than quality.
You can't fit Windows into an embedded device and if the OS can't do the job, cost doesn't matter. There are other OSes that can be had for cheap or free, too.
In comparison to anything Microsoft offer, both the OS and the CPU will be cheaper if they run something like Linux. Cost is the reason manufacturers use it, not necessarily quality.
The cost of the CPU has nothing to do with the operating system unless you mean the computer itself. The reason a Windows box may cost more is because Windows is inefficient and needs more processing power to perform the same task as Linux/Unix/BSD.
It just seems everything in Linux has been made deliberately more difficult to use than it could be.
To the contrary, The Unix Philosophy is to do one thing and do it well and that is true in all things Unix and Unix-like. Every tool in *nix is simple to use and interchangeable with anything else and ultimately customizable. This is not true in any way with Windows.
I don't know if it is a trend but I am seeing the same thing happening in lots of other technology systems usually at the expense of 'looking pretty'.
A lot of people are trying to make technology easier to use for non-tech people. Like Windows 8. But Linux/Unix/BSD can run something just as pretty or run everything from the command line. It's your choice.
*nix is used when real computing is needed because it's the superior operating system. It's easy to get anything to run on it and it's portable among systems. It can be a big system, like most of the world's fastest computers, or very small and can interface to anything (if the manufacturer supplies the driver).
For example, I was in Chicago a few weeks ago and had a document on my office computer. It was in a format that couldn't be read on the Linux notebook I had because it was a custom program. What I did was 'ssh -Y myprogram @18.104.22.168'. That line connected my notebook over the internet to my office computer, started up the custom program and then opened the document I wanted while viewing it in the GUI on my screen as if it were running on my notebook. You can't do that on Windows (and it is NOT the same as 'remote desktop').
You may have missed what I said. Windows is used on desktop computers. It's virtually absent in every other computing environment in the world. That is where Linux/Unix/BSD are and we find it easier to use and superior in every way.