heres the thing you can take a rom on you pc and emulate pixle for pixle at 1080p and it looks as it did on your crt tv clarity/sharpness. Or you can take you snes and hook it up to you 1080p tv and it will look like blurry crap. I played mk1,mk2 when they first came out and the scanlines are not as exaggerated as they are in meme.
I was just saying it's more of an approximation because on an arcade monitor the game did not stretch or upscale or anything it displayed it a the same resolution it was rendered at (512x384). SD content tends to look better on SD monitors as well.
On a higher resolution monitor you will either get pixelation if you use nearest neighbor sampling (basically no bilnear so pixelated.. or as you say.. pixel for pixel) or more blurry if you are using bilinear\trilinear. Either way it has to be scaled up it just depends on the filter used when scaling it that determines how it looks.
The way you say "pixel for pixel" sounds like you prefer nearest neighbor with all the pixelation it entails but at the arcade the RGB monitors didn't display things that way they had lots of blurring going on but the resolution they ran at combined with at least some level of blurring and a high contrast gave the illusion of detail. This is especially true once those monitors got broken in... many arcade monitors had notorious levels of color bleeding\blurring... although they always had brigher colors than home TVs. Yes, nearest neighbor is sharp but it's too sharp... it wasn't that sharp at the arcade. But if that's what you like fine.
The RGB monitors they used at the arcade made a huge difference that is hard to replicate at home.
The SNES versions are blurry crap no matter what because they lowered the resolution of all the artwork in general. There's just no comparison. If you played the SNES version in emulation and did nearest neighbor like how you seem to prefer with the arcade versions it would look even more chunky\pixelated... or again blurry if you are displaying it on a TV especially a CRT.
With LCD screens using scanlines\or some other overlay on MAME it approximates how it looked on an older monitor closer (but not perfect I admit.. you aren't going to get it looking exactly the same as the arcade unless you built a MAME cabinet with a real RGB monitor) sure some of those settings are more exaggerated but you just need to choose the right one with the right settings that looks right on the kind of screen you have and looks fine to you. sdlmame has some really good png based overlays like scanlines or trinitron or other variations. But again this depends on how your LCD displays things and whether or not it processes the image beyond what is done by the computer\game. CRTs especially non-HD ones tend to have at least some level of scanlines going on whether you paid much attention to them or not.
Also this mostly applies to LCD monitors... CRT monitors more closely approximate what was in the arcade for MK but still not exactly. It depends on your monitor and how much color bleeding it does. But TVs just don't do the same sort of display that the old arcade monitors did with their RGB connections and the way overscanning worked making the character look bigger than they really where, etc.
Here is a great example sonic adventures has been unscaled for the 360 and ps3 it looks exactly as it did on my dreamcast on a sony 27crt clarity/sharpness wise.
That's not a good example because those games are 3D and work entirely different than the 2D mortal kombat games. It's much easier to upscale those because in 3D resolution is more independent of the game. That's an apples to oranges comparison. All 3D games need to "upscale" is to increase the frame buffer resolution.
From screenshots i have of mkac they have implemented a blur filter instead of properly up scaling the software.
They are probably just adding bilinear filtering. But on the small pictures of the character select screens it doesn't look all that different to how it's supposed to look... type of monitor it's being displayed on aside.
I too have been playing MK since it first came out btw...