People who have no idea how copyright law works shouldn't just cast judgement and start deleting posts.
Let's talk a little about United States copyright law.
Fact 1:
Any work created after Jan 1, 1978, once "fixed in a tangible medium of expression," does not pass into the public domain until 70 years after the author dies (up to a maximum of 120 years after creation).
Fact 2:
Copyright law gives the owner exclusive rights over a work to reproduce, distribute, prepare derivative works, display publicly, perform publicly, and to perform publicly by means of digital audio transmission.
Fact 3:
You are not required to register a copyright to have copyright protection.
Fact 4:
Commercial copyright violation involving more than 10 copies and a value over $2500 is a felony.
And now the obvious conclusion:
Parts of copyright law (like almost any area of law) are so ridiculous that we can't just look at the law itself, but at precedent of what is and can be enforced. In today's legal system, it is much better to demonstrate precedent than simply attempt to prosecute under any restrictive law that is subject to interpretation.
example:
Technically, having a stereo on in a public place, rolling down your car window so that another person can hear your stereo, or even singing, whistling, or humming a song in public is breaking the law unless the author of the song has been dead 70 years. Obviously, nobody is getting arrested for humming a song. The truth is that copyright law is so loosely enforced that the creator of Napster sold his company for $2 million, even though he should be in prison for felony copyright violation.
Some references:
U.S. Copyright Office
http://lcweb.loc.gov/copyright/
Copyright and Public Domain Information Links
http://www.bf.org/copylaw.htm
So, since there is a difference between what technically violates copyright law and what is legitimately illegal, let's look at enforcement.
No legitimate web site lets you download a new game that isn't shareware/freeware/GNU or just released into the public domain. Certainly you can argue that "warez" sites are everywhere, but people know they are illegal, and they are in no way associated with legitimate websites or attached (knowingly) to corporate sponsorship. Conversely, there are many up-front sites that let you download old games. Whether you want an emulated version of Asteroids or an old Commodore 64 game, you're not going to have much trouble finding it. These things are on public web sites that are in no fear of being shut down.
So, why is that? Let's just use some common sense for a second. Why can you just download a copy of Pong without feeling guilty about it? Is it because nobody renewed the copyright and it became public domain? No. Nolan Bushnell (the author of Pong, although he later admitted he stole the idea from Ralph Baer's prototype Odyssey 100 system) has certainly not been dead for 70 years.
People do not prosecute simply for "copyright violation." To have a case, you have to demonstrate that you were hurt financially by the violation. Copyright violation becomes a felony if it is proven that you have caused $2500 in damages, but if the software isn't even being produced anymore, it is worth nothing, and you can't be prosecuted at all.
You see, people don't often go to the trouble to limit their copyright or release things into the public domain. They just stop making it if it's not bringing in money, and if it's not bringing in money, nobody's going to get sued for copying it.
If you want an old game that is no longer produced, your only options are to copy it or go buy a used copy of it (and unless we're talking about cartridge-based games, you can bet that the original purchaser made a "backup" themselves before selling the game). And if you see a game in some collection of 15-year-old games, do you honestly thing they're paying royalties to the original developers?
So why doesn't someone get Sid Meier on the phone and ask him if he gives a damn about people downloading Civ 1. I'll bet Civ 3 is a little bit better than Civ 1, and chances are he'd love for everybody to get addicted to Civ 1 then go out and spend $49.99 on his new game.