How it it possible that IE10 is still so far behind?

With all those R&D billions, and technicians and programmers and whatnot, how is ti possible that Microsoft is to this day still playing catch-up to other browsers? Opera team has a small fraction of manpower and money, and yet they can write a more functional browser. Sure, it has it's bugs, but all in all, it's a much better experience. Specifically, here I talk about the desktop IE. I don't really know how the mobile version stacks up to mobile competition.

Do they do it on purpose? What is their philosophy on this matter, have they elaborated on it before?

Some huge IE omissions, IMO:

extensions

No matter how many people really use extensions, there are some that are common sense, like adblock. Then there are some others that I use, like email checker and url shortener to name a couple. Every single other browser has them, but MS is ignoring them. Why?

bookmark management

Again, I don't know how much mainstream bookmarking is, but I keep hundreds of bookmarks. Having a nice, clean and fast way to organize them into folders and access them is essential. What they offer in IE is absurd.

speeddial

When I open a browser, I want to be greeted by a thumbnail view of my favourite quick access pages. Instead, IE offers a stupid list of most visited pages, and they keep changing places. Opera has an awesome solution out of the box, others rely on extensions.

session manager

I find surfing in sessions the most productive way for me to skim or check out a large number of news in short time. I launch a news session with a mouse click, and all of my favourite news websites are launched for me to read. It's fast and efficient.

search providers

In opera, I highlight a word or a group of words, and in right click context menu, I can very quickly choose a search engine to find it (ebay, wiki, imdb, whatever..) . In IE, i have to visit the website, coyp, and paste, and than search. It's cumbersome.

wasted space up top

Why does IE keep that completely empty space above tabs? Why not get rid of it?