Two things:
Some of us (especially here) are looking to recreate the original arcade experience perfectly. So we don't want to "improve" the games. Like if I'm playing Metal Slug 2 without the slowdown, it starts to feel like I'm not really playing Metal Slug 2. No thank you.
Translation: I'm a psychopath. We got it. Metal Slug 2 has slowdown because of the technical incompetence of the people who programmed it--NOT because it was some artistic intention that came from meditating in the full lotus position at the top of a mountain. Every Neo Metal Slug is a technical disaster, really. 30hz update sacks of shit. I'm going to get around to fixing that at some point.
And secondly, emulation doesn't fix flicker problems. 99% of the time, emulation CREATES flicker problems. For example, try to find a good version of the Fatal Fury 3 intro on youtube. Can't be done. Every single one anyone has ever posted is fucked up. Why? Because they come from emulation which ruined the car window effect. And I have never encountered a problem with shadows for fighting game characters created with a flicker effect on an MVS cab. I've never encountered a problem with them on a Neo homecart system. But on emulation? Yeah, THAT is where you will find fucked up shadow effects left and right all the time.
Man, you're dumber than a sack of bricks. There is no "flicker" problem. Your shitty Dell laptop runs at 60hz, and the shitty Dell laptop that someone used to record video of FF3 ran at 60hz, and the original hardware runs at ~59.185hz. Yeah, it's not going sync. No shit dude. You also get juddering when the camera pans in movies filmed at 24fps but are displayed at 60hz. It's not an emulation problem. If you have a variable refresh monitor (which you don't--you have a Dell laptop) or run an emulator on a CRT at the right refresh rate, they display perfectly. They're not "shadow effects." It's just a simple matter of the display refresh rate not being an even multiple of the original hardware's refresh rate.
I could put a GroovyMAME computer in a 4 slot cabinet, let you play on it for hours, and you wouldn't even know it wasn't real hardware. You're so full of shit it's pouring out of your ears.
Finally, even though you're so stupid you're not worth my time, copying software is never "stealing." It's copyright infringement. And copyright infringement is a great thing--especially when zombie companies like SNK that still exist in name only are only around to prey on dumb consumers like you who think that buying trash from them makes it "official."
Basically everyone who actually worked on the games we love is retired, dead, or working at a different company. I couldn't give less of a fuck about whether the current suits running a different company that just happens to be called SNK get to cash in on shitty Nintendo digital store re-releases or vomit inducing mobile games.
In other words, sit on my cock and rotate.