I believe that abandonware should be made legal and I will try to explain my reasons here.
First things first – what exactly is abandonware? Well, that's where the problem already begins. There are a few diverse views on what abandonware is, which I'll name, but later on focus on what I feel is the most realisticly practical and logical one.
The most broad (and potentially most dangerous) view on it is that abandonware is every piece of software that is older then a certain amount of time (usually 5 years) – not heeding whether the owning company still supports and/or sells it or not. A more down-to-earth approach to it is that it is software that the company holding it under copyright has stopped distributing and/or supporting it and has done so already for a reasonable amount of time. – This is the view that I support and under which I will base my article. The most narrow view on it is that abandonware is software that its copyright holder has re-licensed or otherwise made accessible to the general public. This definition is impractical, because there's no single way how copyright holders can do this and because of it this definition doesn't serve any practical purpose.
Even the ancient romans protected the non-owning possessor from the non-possessing owner if the owner didn't take care of his possession for a longer time. And to back that thought up even more, quite a few iurisdictions allow copying for personal use literary works that haven't been printed or distributed anymore for a period of time .
So, it's obvious that the idea of not protecting copyright completely without any restriction is not a revolutionary new one.
Also an importaint factor is that software gets outdated faster than other litterary works (e.g poems, novels, theatrical plays, etc.). There are not many people playing ten or more year old games and using so old software. An even bigger problem usually is backwards incompatibility. Since the IT is evolving at a mind-boggling velocity and not in a single straight line, it's very common that only slightly older software cannot be used on contemporary hardware and/or togther with contemporary software. Which makes it quite useless pretty fast.
It has to be noted that (some) iursdictions support motive of interoperability as a legal exeption from the copyright, meaning one is allowed to (for lack of a better term) "bypass" the copyright of a piece of software in order to gain knowledge how it works and how to make it work in other situations (i.e. on other hardware, with other software, etc.) or how to make another piece of software work in a similar situation as the examined piece. The downside is that interoperability is not used fully in the court practices, and hence cannot be a 100% reliable reason. Plus in my experience I've seen some great projects that wanted to make an old piece of software work on modern systems abruptly stop because the copyright holder of the software was against such action.
I dare conclude from all this, that abandonware really is needed, but that leaves us with the question of how to do it in the best manner possible.
The solution I deem is the most fruitful, probable to come true and fair is that software should after a fixed amount of time lose the part of its copyright which stops other people from distributing it and (if need be) decompile it in order to make it interoperable with contemporary systems. Of course, this time would have to be counted only after it was obvious that the copyright holder stopped distributing and (commercially) supporting the said piece of software.
It's completely ridiculous to vehemently defend copyright and thus completely disable later generations – and actually the same generation as well!! – from getting hold of and using older software, no-one makes or supports anymore.
In any case, we're up for some really interesting times concerning the so called cyberlaw in its broadest meaning.