Everything in context. It is huge for Microsoft specifically because it's previously been so entangled. Progress is good on all fronts. For the very large portion of the world that uses IE by default and will in the future get faster/better upgrades to be more secure and more full-featured, this is great.

Entangled is a very kind word, almost sounds accidental, when the anti-trust stuff found it was all very much on purpose.

Exactly, IE has come a long ways in the past few versions, but it's still behind other modern browsers. It makes me wonder why MS is still pushing it. Why not just bundle another browser with Windows and save themselves some effort?

Probably for the same reason Apple and Google both produce their own browser - it's too important a part of the user experience to delegate responsibility for it to a third party.

It's unlikely Google would suddenly turn around and say they're no longer producing Chrome for Windows, for example, but it's not impossible.

Also, IE, or rather Trident, is a core OS component. Applications rely on it for displaying web pages and HTML. Applications can also be written in HTML and JS, both HTML Applications (since... Windows 98, I think?) and WinRT applications (since Windows 8).

I never understood why they simply could not use Trident for OS calls and let IE have its own engine. It seems like such a straightforward solution.

It is like building a computer and soldering in the GPU, just because you want to reference the PCI port statically.

The main IE components has been in System32 since IE3 I think.

Yeah you're probably right. They want the experience to be cohesive with the rest of Windows. Last time I looked Chrome still doesn't have a metro mode besides just opening up in full screen mode, so there's one reason to keep IE around