Youi're missing the point: This is not being added because people use Cortana much (Win 10 hasn't even been released yet!) but it's another strategy to get you to use it more.
Microsoft has done many things in Win 10 to tempt you to use their services (e.g.: search searches the web by default using Bing, OneDrive can't be uninstalled,..) and I hate it

+1. I'd also pay money to Google to be able to use Android without any of their apps (i.e.:being able to uninstall those I don't use).
I'd also pay money to Microsoft for a Windows 10 without any of their services (Bing, Onedrive, Store, Cortana)

No, all are the same thing: a means to get more money.
The difference is that Windows didn't use to have it and now does, and moving solitare to the store isn't done for technical reasons but for forcing you to use the store

Yeah, DirectX 12 is the only reason I see to upgrade. And it irks me to no end the fact that I'll have to use a OS worse than Win7 (IMO) to get it

Yeah, it's a political removal. The only reason to do this is to force people to go to the Store to download it and get them used to get "apps" of which any sales Microsoft will keep a 30% cut

Hey, don't complain!, it's for your own *cough Microsoft's *cough benefit ;)

I read somewhere that, while developing Windows 8, it was found in internal testing that most people hated the Metro interface. They kept it anyway.
The takeaway is that they did test and tests were negative but they went on for business reasons.
They want you to get used to the metro UI so that you'll get used to it and you'll buy a Windows Phone phone. Also so that you buy metro apps through their store and they get a 30% cut, so that you use their services and they get your data and money , etc.
TL;DR: They know it sucks but they want the money they think it'll make them

Exactly! Seems like the motto is :"One true,flat,ugly way".

+1000. I completely hate the modern UIs made to be usable on anything. They're jack of all trades master of none, and of course, less optimal for desktop use that the previous ones which were tailored for them.
Now every UI is:

1. Flat (no way to know what's clickable and what isn't)
2. simple, flat colors
3. has tons of whitespace

We'd be better off with separate UIs for touch and desktop

Where are my mod points when I need them?
Totally agree. Windows 7 is an OS that does what's supposed to: Stay away and let you do your work. Windows 10 is a giant advertisement for Microsoft services: Don't like OneDrive? Sorry you can't uninstall it. Don't want to use Bing search? Sorry it's baked in to run when you try to do a search on your computer.
You even get suggestions (ads) for apps on the Start Menu! Also it's a bipolar UI, an unholy mix of touch/mobile and desktop flavors and applications and even in the desktop you're sometimes forced to use a touch UI for some tasks.
Windows 7 was a nice OS for users, Win 10 it's only for Microsoft sake, no wonder it's a free upgrade: They're hoping to get the money from you through your data, the money they'll get from you using their services, etc...

Not much to add except that I'd upmod you instead of commenting if I had points.
I too find horrible that they're going in the direction of less customization. It seems they want to be like Apple and are copying the worst things of them (e.g. the little customization). They also invent new horrible ideas of their own like making apps with and interface that's not touch nor desktop but in-between and claiming they're as good as specfic interfaces for each UI paradigm (which of course are not)

Not only this mobile first crap has ruined many websites, it's also ruined Windows (see 8 and newer). It's a horrible plague

The EU press release (http://europa.eu/rapid/press-release_MEMO-15-4782_en.htm) mentions it received two complaints regarding Google and Android.
I wonder who might have initiated them (maybe Apple and Microsoft?).
The allegations revolve around the infamous agreement manufacturers have to sign if they want to include any Google apps in their Android devices (including the Play store, Gmail, Youtube, etc...). If you don't know it states that if you want to include any of Google's apps you must include a certain group of them (it was around 15 I think). It also states that you shall not develop any Android forks.
I do agree this agreement is abuse of power and I'd really like it if this resulted in we being able to uninstall (without rooting or other trickery) Google apps from Android devices, even if it means I have to pay some money to Google for the base OS.

I'd say no. See what they've done with Windows 10? It's intimately tied to Microsoft's services (Bing, Cortana, OneDrive, Microsoft Accounts). You can't even remove OneDrive from the list of "fast links" on the left pane of the Windows explorer in Win10.
Microsoft seems to want to become Google (making money off people's data) and I personally hate it. Windows 7 is a nice OS which does what a OS is supposed to, i.e.: manage your hardware and run your programs while getting out of the way. Win 8 and 10 look like a giant advertisement for Microsoft's services.

Totally agree. At least Linux has no concept of "default UI" and is thus easy to choose the one that fits you best.
Windows, OTOH, is designed with the notion that you will use the UI provided by Microsoft and is not as easy to change. Add that to the fact that I really don't like the direction Win10 is going and I honestly don't know what I'm going to use once Windows 7 is too old, i.e.: Doesn't play nice with new hardware