I applaud your efforts to do the right thing. The only reason I can give you, is that you support piracy by downloading roms. You add to the popularity of them, adding another download to the tally, justifying others to do the same. Others that might not own a legal copy.

To give an analogy. Over the years I have found that the best way to keep a publicly accessible space clean is not by putting up signs or bins etc, but by making sure it is clean in the first place. When people see other people do something, they'll more inclined to do it themselves. When they find it neat and tidy, they tend to want to keep it that way.  If I clean it straigh way in spring I maybe take out a small plastic bag of trash and it stays nice. Wait a few weeks and there's a garbage bag full of crap around. It multiplies!

By downloading the Rom you legitimize downloading said roms in the eyes of others. So yes, ethically there is a small difference. Which is also why using emulators for brand new games shouldn't be advertised. Monkey see, monkey does. That's the human race.

You can use VMWare for piracy by downloading the operating systems off the internet, which is something I would wager that most people who use VMWare do. (Italics) Using VMWare you can run OSX (or previous Apple OSes) on a non-Apple computer, this is something which violates the EULA. DOSBox is used by companies to run some of their games but there is nothing preventing you from using pirated PC games on it either.

So I am unsure why you think there is a distinction here.

Yeah, that was the only reason I could think of as well.  But honestly that argument doesn't hold much weight with me. I just did a quick search for the Skyward Sword ISO, since I don't remember where I got it from.  None of the sites showed a download tally of any kind.  I'll admit I didn't spend much time looking, though.  So if we're talking about a download tally only visible to the owner of the site, then I suppose the owner would see an additional download from me.  So in some miniscule way, I have validated the pirate's existence. Though I doubt I was the "make or break" statistic for any of the Wii or Gamecube games I have downloaded.  PS1/PS2 games I always ripped on my own.  And I suppose you could also make the argument that I am indirectly supporting piracy by giving one more download for Rawdump, which is the program I use to rip my Wii games today.  But people are going to rip and pirate whether or not I download or rip games I have already paid for.  I'm a small non-existent drop in the bucket of the piracy world.

The problem with that analogy is you're not committing a crime using an emulator, the crime is from software piracy. It would be akin to buying a gun legally but obtaining the ammunition from an illegal source. Or more simply, it's like buying a PC but then illegally downloading all of your games (or programs).

Considering companies' stance on emulation, I doubt we would get much cooperation from them.  Usually they employ more of a "cease and desist" kind of solution to these things.  

Also, and I don't know if this has changed much over the years, but performance was often slower if the game was read directly from the disc.  So if some kind of copy protection were to be used, it would be nice if the game could still be run from an ISO, but would check for the existence of a disc.

I'd argue that they shouldn't even bother. Even if piracy itself is a problem, the amount of lost sales from people pirating a game for emulation is dwarfed by the amount of people who download the game illegaly on cracked consoles or on PCs. You cannot emulate PS4 games right now, but you can pirate PS4 games. Even for new games like Persona 5 or BotW (which are exceptions to the rule of emulation), it's still a work in progress to get them running and you need a powerful PC, someone who simply wants to pirate the games will just use a cracked console instead, and they do. I don't think emulation itself is that big of a problem that needs intervention.

Enforcing those standards on emulators would completely redefine on how you can use software in any way, by giving companies more right and eroding consumer rights. This would do nothing to curb piracy, any system can be and will be cracked. At the end of the day these measures would only hurt the legal consumer while doing nothing to stop pirates.

Emulators are just a tool, I don't think that the emulator creator bears any liability for the same reason I don't believe a gun manufacturer has liability for how people use a gun. In the end, the benefits from both tools outweigh the negatives that may arise. Especially for software which is so easy to lose forever and it seems that companies are not very good at maintaining databases (see the Eurogamer video on the VC version of Super Mario Bros. which suggests they used a ROM they got off the internet).

Nature of capitalism really. Still, companies could take note of demand and offer their own legal emulators and ROMs which SEGA and SNK do on Steam.

I miss the days where companies would put their retro games into a compilation instead of selling them separately. I liked SNK Arcade Classics and Sonic's Ultimate Genesis Collection.

Yeah I think those days are long gone now because of digital marketplaces, but sometimes you'll see something like Mega Man Legacy Collection once in a blue moon.

Question for everyone who says emulation = piracy... how exactly does one "pirate" software that has been out of print for decades and can only be obtained in physical form on the 2nd hand market via private sale or professional resellers looking to make a mint off the most popular and rare / obscure titles out there?

Emulation is not the same thing as downloading "ripped" or "cracked" copies of currently published titles off torrent sites on your PC, or modding your console to play burned discs of said copies. As long as the console & software are no longer being produced, and the emulation programs and ROM files aren't locked behind some sort of paywall, there is nothing wrong with emulation.