If I understand what you're saying, you mean you can run original games on an emulator with no problem. I'd assume that's correct.
Seeing that Nintendo only switched to disc format 6 years ago, anything prior to that would be much harder to 'play the original' on an emulator. Most people don't have the hardware to do that.
With Nintendo's Virtual Console--and Xbox Live to an extent--they're getting around that 'This game is old and I can't buy it anymore so I'll just download it for free' idea. At least in Nintendo's case, as long as the company is in business, all of their games since Day 1 of their existence are protected by copyright laws.
Granted, right now Nintendo probably isn't too concerned with pursuing us with their current success. Unless you're modding your console.
No matter how you personally define it, getting something for free that you would usually have to pay for (regardless of availability in the physical world) is stealing. Piracy is just a generalised term attached to that. I think it's important for those of us who do this kind of stuff (games, music, movies, softwarez, anime, etc) know that it is just plain illegal, and treat it as such. If you have old games, talking about them is fine, but don't make it a point to say that you're playing it on an emulator. Chances they'll come chase you are still low, but you don't need to be waving a flag at them saying 'I stole your old stuff nyah'.