Technically Abandonware is a legal grey area, but how is it morally? I view it to be a helpful promotional tool for future products.
Shadowrun (for Genesis) is the game that introduced me to the Shadowrun series. I'd buy a sourcebook if I had the cash lying around, could find it, and would actually use it, and I frequent the novels and fanfic of it. I'd even buy the 360/PC Shadowrun if it weren't M$ crap (Still not buying their games often since MechAssault, those heathen heretics who defaned a good series). That's how awesome it was. Oh, and, whoever owns the rights, if you actually care, contact me with legal proof and an address and I'll mail you $50, when I get a chance.
RPG Maker (95/2k/2k3) is an iffy area also. Abandonware is technically a commercial product abandoned by its maker, but what is something never released? Now, I know that it was released. In Japanese. I know a bit of Romanized Japanese (Ok, so virtually nil, but I can pick it out from other languages), but I won't learn a language to buy a product to make games. Much less when my target denomination would suffer. However, the pirate versions of RPG Maker serve very well as marketing tools for the later, legal, English releases.
Abandonware is, in my opinion, legal and right. It's not like you can't protect your products, give them away later, or even just release them everywhere, or join a coalition to have your things removed (Also, mind you direct contact to distributors will stop true Abandonware, as opposed to blatant piracy) to prevent people wanting to enjoy ancient games from enjoying them, and considering buying other products or your later products.