Re: "need to stop being lazy and port to Mac and Linux"
@LDS.... lot of Linux myths there.
Linux users don't buy software, for one. The average Linux steam user outspends the average Windows user. Not everyone is Richard Stallman-- many of us are in Linux-land not because of some fanatical devotion to the tenets of open source, but because we're sick of Microsoft's crap.
Application developers need not fear GPL. I don't know why people are so prone to overstate it, but if you're not taking GPL code and redistributing it, you're fine. Is it really better to develop for closed-source platforms from companies that think they can patent things like rounded corners? Software patents ought not be a thing, but they are, in the US at least.
I'd be interested in seeing any surveys you may have about Linux people being more interested in the command line. I see a lot of interest in desktop environments and graphical tools. I'm certainly not itching to open a terminal window at every opportunity. I use the terminal when I have to, not because I am interested in it. I'm interested in getting things done, and whatever tool allows me to do that as efficiently as possible is what I use.
Applications in Linux are mostly ugly. I'm not seeing it! Firefox looks like it does in Windows (ok, bad example; Firefox has been ugly since Australis landed), and so does Thunderbird. Qt looks like the theme you've assigned to it... if it's ugly, you probably need a new theme. Now, I will say the GNOME programs (not apps, it's not a damn phone) with their CSDs and hamburger menus are ugly, but not as ugly as anything UWP. UWP sets a new standard of dingy, space-wasting, unintuitive, "it looks like something broke" ugliness. At least GNOME CSD header bars are themeable.
Text-based applications? Other than "quickie" single-purpose tools for which I can't find a graphical alternative, I think the last text application I used may have been Telix, back in the MS-DOS days.
Windows is ahead of Linux in GUIs? Have you SEEN Windows 10? It's the ugliest, most disjointed piece of crap masquerading as an OS I have ever seen. You could pick a Linux DE at random and end up with something better than Windows 10. I'd take Cinnamon, KDE Plasma, Xfce over Windows 10 any day of the week... and in fact I have used all three of those instead of 10. KDE Plasma makes Windows feel antiquated and stifling by comparison. All three of those DEs (suitably themed) are far more attractive than Windows 10. It's hard to imagine anything that isn't. UWP seems to be singularly designed to maximize hideousness.
Speaking of themes, you don't have to hack the OS in Linux to be able to modify the theme as you do with any currently supported Windows version. Just getting rid of the blinding white backgrounds in Windows 10 requires intervention to get the OS to stop blocking your theme because MS is more concerned about branding than serving their users. They've decided that this is the "look of Windows," and everyone is going to be forced to use it. That's part of proprietary software-- the maker is always going to be looking to benefit themselves, and third-parties and end users alike often suffer.
Gabe Newell at Valve, who makes a living selling software and helping other game companies to sell software, isn't afraid of Linux. He's more concerned that MS is going to deprecate Win32 bit by bit in favor of UWP, then close the door to sideloading, so that all Windows programs are UWP and all UWP programs come from the MS Store, as it is with Apple and the App Store and iOS. That's clearly the model for MS, even though iOS is a mobile platform and Windows isn't anymore. Supporting Linux means no one can corner the market on software and lock everyone into their fiefdom!
Developing for Linux means ongoing freedom for third-party software companies to make money without bowing at the MS altar and paying their tribute as devs have to do to get their apps in Apple's App Store. Linux can never be locked down by a single company in that way, for precisely the same reason that companies are supposedly afraid of Linux (the GPL).
Even if you're not interested in gaming at all, the principles are the same with any other kind of program. If Microsoft can lock gamers into the Microsoft Store, they can do the same with users every other kind of application. Developing for Linux doesn't have to make a ton of money in and of itself if it prevents Microsoft from being able to consolidate everything in a way that favors them and harms everyone else. As long as people have a viable alternative to Windows, Microsoft won't be able to create the walled garden they so desperately want. It doesn't matter if the share is 4%... if businesses/gamers/etc. see Linux as a real option, it limits what MS can get away with, and that's good for people who sell software on Windows. So many people say they hate Windows 10, but they can't leave because the programs they absolutely need are not available elsewhere. Microsoft knows this very, very well; it's why they act as they do.
How much more pleasant would Windows be if people did have a choice? If their favorite programs were on Linux, Windows would not be the pain train for users that it is now. That train hasn't reached its destination yet either... it's only going to get worse and worse. They don't even have half the Windows users on 10 yet, but that's only a matter of time. If they act this way now, how will it be when 80% are using 10? The only competition for Windows 10 right now is Windows 7, and the clock is ticking. MS is not afraid of people moving to Linux. We'd all be better off if they were (excluding MS itself, of course). Developing for Linux is an investment in being able to keep making money from Windows users.