Thanks for the thoughtful comments, they are very much appreciated.
The thing that a lot of Linux developers don't seem to get about Windows is that its binary distribution model is an opportunity/productivity multiplier, and it all hinges on three major points:
1) Backward-compatibility is real, and, contrary to what most people say about MS/Windows, this is very pro-consumer. Just chucking code at people and saying "but, you can just re-compile it" ignores a lot of realities, including the fact that even developers don't want to be forced to recompile binaries that they are not, themselves, working on as their actual work.
2) You can deploy 32-bit binaries on 64-bit systems and they work just fine. It really made the switch to 64-bit versions of Windows a non-event, whereas this is another issue that developers need to worry about when targeting Linux. And, there are a lot of applications that simply don't benefit from being 64-bit because they don't need, or can't use, the increased address space, so forcing developers to specifically target 64-bit is just another unnecessary hurdle.
3) You can actually create binaries for Windows that don't require any dependencies other than what is available in the OS. This means that you can create binaries that work on tablets, laptops, desktops, and servers without recompilation. This also ties in to your comment about the installers, but the reality is that you really only need admin access for an installer to put things into the "Program Files" folder tree, or to install services. Apart from that, most professional software doesn't touch anything other than the user-specific folders (if Windows doesn't delete them first ;-) ).
I don't think that this point can be overstated: if you create a neutral OS platform where desktop developers can deploy their software with minimal fuss and no gatekeepers, you will win the desktop space, period. More than anything else, desktop developers want to make money, and an open OS that does its thing and stays out of the way is the ticket to that money. But, in order to do this, a lot of current Linux developers will need to get used to sharing Linux with commercial vendors and proprietary software, and I think that's still a hard sell. And, unfortunately, a large part of that mindset is wedded to this bizarre idea that desktop developers like Windows because of Windows. Desktop developers like Windows because a) that's where the users are, and b) they can make money without being forced or required to expose their source code. If the same can be done with Linux, then Linux will have no problem taking the OS space away from MS completely.
Linux is stuck in "server/appliance mode" right now, and it's a shame because if there was ever a time for Linux to take over the desktop, it's now. As you say, web applications are just not a suitable replacement for all desktop applications. MS keeps trying to lock down how development is done on Windows and, if they succeed, then everything that I stated above will go away and there will be a lot of developers looking for a new home. Any OS that starts out with "you can only use our development tools/languages, and no others", is going to whither away and die. It happened to Apple once, it appears to be happening to Apple again, and MS has apparently decided that it should emulate Apple. The whole reason why Windows became popular in the first place was because there were a ton of development tools/compilers/languages that could be used to produce binaries for Windows, and Windows gave zero preference to any of them. This was carried over from MS-DOS. And, none of this precluded any vendor from going ahead and providing/selling their source code along with the product. Linux developers have just got to let go of trying to control how people use the OS, and just try to make it as amenable to as many usage/deployment scenarios as possible.