PS+ and Steam sales would disagree with your statement.

I don't plan on upgrading from Windows 7 for a good while. Windows 8 will be the last thing I think about when I finally get around to building my new rig.

Lol What is that?

A lot of people including myself installed it anyway even by knowing it would require a high end PC to run smoothly and nobody is complaining about it so why on earth are you replying that. The point is that a lot of people did that just to see the graphics (as I did) but cannot effectively run the game smoothly with it. So your 1M figure is just plain wrong.

Ignoring the high-end PC market in favor of parity is your own making by the way. Apart of rumors and conspiration theories out there, nothing is proving that. 
The most obvious reason is that instead of wasting developper's capacity on something a very low % of customers will use, they spend more time for content or other features... Again you completly ignored my point which was: more content/features > super ubber very high settings stuff... 

Big difference between a mod that is free ad infinitum and an entire game that you can only download for that low price at a certain time.

To each his own though.

And you ginored my point as well, which was the exact same thing, as I've posted at least three times in this thread. 

My 1M figure is still relevent, since the vast majority downloaded it because they could use it, not just for fun.

And Watch Dogs and Far Cry 3 beautifully illustrate my point that parity is alive and well in a very sickening way.

Replace a game on sale with MMO (a lot of people download multiple free-to-play MMOs, but never get around to playing them) and my point still remains true.

Not sure what you're trying to say, because your original point was getting a free mod that takes maybe a minute tops to download with a manager vs getting an entire game for free or for practically free on a sale.

Also, most people don't just download MMOs and never play them. MMOs are big, take a long time to download, and require a lot of disc space. If you aren't planning on playing it, you usually won't download it.

It will look better in many ways. Things like animation, dynamism of the world, physics and lighting should be better in ways that modders can't do without full source access.

Agree with you on the physics and animation, I dunno about the dynamism and lighting though. Modders have blown it out of the part with amazing ENBs that add truly beautiful lighting, and there are too many world mods that make the game much more immersive.

But you're right about the physics and animation, only Bethesda can improve on those.

That wasn't my original point, actually. You said that most gamers don't download things that they aren't going to use for months (or even years as you put it), yet gamers do it all the time. I was merely pointing out the different ways that you were wrong. Whether it's a mod, a free game, a discounted game, or a free-to-play game is irrelevant.

And you keep talking about "people" as if you know what everyone does. You obviously don't. And yes, many people do download free to play games, but end up not playing them for different reasons. But that's beside the point.

It doesn't matter how good they'll manage to make the graphics.
They have to make a respectable gameplay/combat and not that thing.
Can the mods improve the gameplay?

I'm honestly asking here...

It did for The Witcher 2. It just depends on what modders want to do. And there are numerous new attacks created for Skyrim through mods already. I don't know if any were made to alter/improve the core gameplay though.