Emulation has been deemed legal? Since when? You're not paying for the system or the games and playing them freely?
For instance, I run qemu all the time to emulate various android devices.
I suspect that you're thinking specifically of game emulation though.
Running software on an emulated device is fine legally as long as it doesn't violate copyright law.
For instance, you can legally backup software that you own in the US [1] - that extends to games as well - and because emulators themselves are legal (although you may also need to backup the device's BIOS), you can have a completely legitimate archive of copyrighted games to run via an emulator.
That said, it's unlikely that most people archive software themselves, and it is not legal to distribute backups in the US, even if both parties have legitimately acquired copies of the source material.
Do you (or anyone) know if caselaw on this point and which USC this position relies on, thanks.
Torrenting also isn't illegal by itself or a direct link to pirating, it is just a very common way of sharing pirated data.
Emulating also isn't illegal by itself of a direct link to pirating, it is just a very common way of playing pirated games.
Just as you can go to to arch linux' web page and download through their recommended method (torrent), you can go play old PS1 games on the PSClassic (based on the PCSX emulator), or play GB/GBC games on your 3DS Virtual Console (in house nintendo-made emulator afaik, correct me if I'm wrong).
I was making fun of that comment to point out the same is true of emulation. However I obviously misinterpreted the initial comment since you're clearly aware emulation itself is legal. Sorry.
2. This way you can buy physical copies of games, keeping full control and the ability to resell them, while also carrying your current game library on an SD card.
Edit: I forgot modding! That's a huge use of emulation.