First, I do play at 4k. The only issue with 1080p vs 4k with most modern videocards is how much RAM the card has. 4GB is more than enough to play 4k flawlessly.
Second, Skyrim modded like that is easily current graphically. If you say it isn't, you don't know the first thing about modded gaming.
Third, I just looked through and I actually spent closer to $650 for all that, plus tax.
I know how mods work, I used enough of them for my Skyrim and Oblivion experiences. They're nothing more than window dressing in the grand scheme. They don't change the core of the game. Prettier textures won't do a number on your GPU, that is true. Still, there is a reason why the currently strongest Single GPU on the market has troubles to even get to 30fps@4k with anything that isn't a pushover like Skyrim.
Comparing a modded old game that was already a technical underachievement when it came out with any current game is a joke.
And I thought current games were the topic of this thread.