The desktop PC I've built earlier this year has spoiled me..
I just don't require that much power for a device, but I still would want to buy this just because haha.
X1 Carbon is my work laptop which is i5/8GB RAM/256 GB SSD and I think either thinner or lighter than an MBA.
My desktop is i5/16GB RAM/256 GB SSD + 1 TB HDD/R9 280 3GB GDDR
Then I have a Galaxy Tab S2, which is the thinnest tablet in the world, very light, feels great in the hand, and has awesome performance. I use this for some light android gaming like Kingdom Rush when I'm at home and for web browsing/reading/film watching when I travel or when I'm laying in bed.
So therefore, the Surface Pro 3/4 is the ultimate "I don't need at all, but want this shit" device for me. If anything if I was able to find a crazy deal, on a Surface Pro 3. I would be tempted to buy it and sell my Tab S2.