The age of abandonware titles and their lack of legitimate availability distinguishes them from what people mean when they talk about pirated games or "warez," which are newer games made available illegally despite still being in print.
Abandonware sites will often remove any software that's disputed by a company, and some will go so far as to place links to the official sites where you can buy the removed game. Some sites will put disclaimers up saying the downloads are only legal for people who own a legitimate copy of the game. They also tend to stick to rules such as only hosting games that are at least several years old and are not available through official channels (as far as they can tell) to distance themselves from pirate sites. Some abandonware sites operate outside of U.S. borders, although U.S. copyright is enforceable in a lot of other countries [sources: Moby Games, Smith].
Advocates for the ability to freely distribute and use abandonware argue that copyright is far too long these days. In 1790, U.S. copyright was 14 years plus one additional period of 14 years if the author renewed, after which the work would fall into the public domain. It has been extended several times since then, and now can potentially last more than 100 years, longer than video games have even existed.
Some fear that if abandoned games do not go out of copyright in a reasonable period, and no one is technically allowed to distribute or download them but the owner, a lot of games will be lost forever, especially given the short shelf-life of computer systems and software and the inevitable degradation of the storage media. For example, in 1996, Polarware (formerly Penguin Software), which produced adventure games in the '80s, released the rights to all their software, but even creator Mark Pelczarski didn't have copies of all of them at that point [source: Moby Games]. Many popular older games whose copyrights are held by existing companies are available for newer platforms, fortunately. But more obscure titles, especially those created by companies that disappeared, run the risk of being lost to time.
Other reasons for making abandonware available include opening it for scholarly study and historical analysis, and for study by game developers who want to improve their skills. Most artists at some point study previous artists' work, and software is a multi-faceted art that includes visual design, music, interactive storytelling and computer science.
And of course, sometimes people just want to relive their favorite games. The very existence and prevalence of abandonware sites point to the fact that there's a market for older games. The popularity of an abandonware title can even give companies information about what titles to re-release. This happened in 1999 when Hasbro released a new version of the 1981 Konami game "Frogger" after noticing that it was still popular. The new version was in the top 10 best-selling games that year [source: Costikyan].