I'm a plugin author with 7 plugins in the Repository, published over the last 18 months. I have seriously considered adopting a few plugins that could be easily made to work properly, but haven't been touched by their authors for two or more years. But my definition of adoption is different. And might make acceptance by the author easier to come by.

I always wanted to be another author, and wouldn't dream of having the original author's name removed from the repository listing, as he/she deserves the credit. Which is why I've generally shied away from forking.

As for contacting the original author, allowing existing plugin authors who meet some criteria (e.g. - have updated at least one of their plugins -- maybe just the readme.txt to say it works with the current version of WordPress -- in the last 6 months) to do this themselves, with no intervention by WordPress folks. Without revealing the e-mail address of the original author, but with some feedback if the e-mail bounces, so they know the e-mail address is likely out of date, but definitely did not reach its destination, allowing them to try some detective work of their own to try and find the author. If this is not enough to prevent spamming, then some sort of automatic monitoring that shuts anyone down who contacts more than say a half dozen authors in a 48 hour period might work.

But, in the final analysis, I'm just another person who hopes perhaps against hope that there is a way to improve the quality of plugins from the perspective of the person trying to just find a plugin that performs a particular function, install it, and forget about it.