Even if LinkedIn or Twitter were open source, I would still not be able to control them--I don't have a spare server lying around and I certainly don't have a way to get everybody else on my own system! So if I took LinkedIn's source and improved it, it would be useless: I would first have to get a server to run it and then I would have to get everybody I know to switch to it. This means that, even if LinkedIn was open source, I would still have to use their implementation on their servers; it would not have much of a practical effect.
Put another way, Reddit and HN are open source. But this does not mean I can meaningfully modify or control the code; this control is naturally left to the people with the servers. There is very little practical difference for me as a user between an open source Reddit and a closed source Reddit.
Now, this is not to say that web apps should not be open sourced--quite the contrary! Open sourcing is great for reasons besides freedom: you contribute to the common good, give more people insight into the development process and help other people with similar projects. But it is less critical than having open source programs that run on my own computer.
Secondly, because there aren't adequate F/OSS replacements available. I can use Fedora Linux with KDE and get an experience that's better than Windows. I don't know of a Quora like service that makes their code available, that gives a better experience than Quora. That said, if such a thing were available, I would prefer it.
But I like my own freedoms and I'll avoid buying software that prevents me from exercising them.
But they also tend to be the people most invested in the software itself, so if you're a company that sells software you should probably torment them at your peril. Drive them away without successfully luring any new users, and you may not end up with very many at the end of the transaction.
The caveat, of course, is that, just because something is better for most people doesn't mean it will be better for all. And, of course, there is a large group of people who just refuse to accept change.
(I've used the Office ribbon exactly once and couldn't figure out what I needed to do. I don't consider myself well versed enough to say whether it is innovative or not.)
But Office on the PC wasn't made for a tablet - they intended the ribbon to be used by PC users, and it's terrible. Removing the menus eliminates discover-ability. The common case now when using a recent ribbon-enabled Office application, for me at least, is vaguely recalling a function that I used in a previous version and then hunting around for 2 or 3 minutes through the UI and not finding it. Without doing google searches, I'd never be able to find these features. And each of these feature-hunts adds up to a lot of wasted time.
The ribbon is a massive, massive step up in usability, the difference is you already knew how to get to features in the old version, so there was a learning curve. Show two people who are brand new to office Office XP vs Office 2010, and I an completely certain that they'll have an easier time with 2010 (especially Excel, the usability difference there is incredible).
Sure, if you use the "more frequently used options" but try using something a bit more obscure and you are out of luck.
At least with the menu system you had those "breadcrumbs" to give you an idea of where it could be.
If you're trying to do anything other than the obvious stuff, then yes. I struggle to find anything in Office w/ Ribbon, whereas I could almost always find what I was looking for in a few seconds worth of menu hunting before. Personally, I find discoverability to be absolute shyte with the Ribbon interface.
But, I only use Windows at my dayjob where I have no choice, and I try to spend as little time as possible paying attention to the fact that it's Windows (hello, Cygwin). I'm probably not exactly the target market for MS on this to begin with. ;-)
I am not adverse to change, and had a very open mind about the ribbon in office, but it still hinders me far more than it ever helped. From observations of others there are perilously few who actually appreciate that interface tactic.
Bleah. Here's a thought: "Newer" and "innovative" do not necessarily equal "better." As far as I'm concerned, the Ribbon UI sucks big hairy ones, and is just one more reason to run screaming away from Windows 8.
Then again, since Windows 8 isn't F/OSS, I have exactly zero interest in running it to begin with, so MS aren't losing a customer here.