@helvetica: All of the games mentioned in this thread were free. Nobody was requesting for this site to be turned into another "abandonware" repository, that would benefit nobody.
Piracy is piracy, and there are hundreds of sites dedicated to that sort of stuff. There are already plenty of places where people can find and post ""preserved"" doujin and other japanese computer games.
Many other sites and forums have strict anti-piracy rules. It's already hard enough to find an opportunity to link to this forum elsewhere. I would greatly appreciate if this wasn't made even harder by the risk of us getting warned or even banned from such places for trying to promote this community.
As for the original topic on free games, one of the reasons why rehosting is frowned upon is because of page views and download numbers.
By keeping track of these, you can have a rough idea of how many people are interested on your game and/or enjoy your work. For many, this serves as a major source of motivation to continue making things, even if nobody comments on them! For this reason, rehosting should be avoided unless it's absolutely necessary.
If the author's site or the game files don't mention redistribution, I think rehosting is fine if the site dies (or if they don't have a site, if their download links stop working), specially if the files were hosted on a free host. In this case nobody should care since the views can't be tracked anymore, unless the author decides to complain.
I remember the UTG Software site went offline because he didn't want to pay for the server bills (?). He actually made an announcement before it went offline. Redistribution of his games was originally forbidden, but I think he decided to allow redistribution when he made this announcement for as long as the contents of the ZIP files are left intact.
The Phantasmagoria Trues files don't forbid redistribution.
If the author tells you to ask for permission before redistributing, you should obviously try to do that. If they don't reply or if they forbid redistribution but their site/download links have been dead for a long time, it's really up to you to decide what to do. Not redistributing is the right thing to do, but at the same time the author may never come back, and well, this is MotK, we've had rips of ZUN's resources and danmakufu scripts using them since forever even though his guidelines have been translated for about 10 years...
I strongly recommend against contacting people about doujin games and music that were sold. If they aren't already available for free to the japanese it's extremely unlikely that they'll be made available to the side of the community that's infamous for piracy and not respecting anything. Plus if a game hasn't been sold for a while (not even at Comiket), there's a good chance that the authors simply don't care about (or want, for whatever reason) people playing these old games anymore.