People work on Wikipedia because they enjoy it. As soon as you start forcing responsibilities the fun factor is gone. We definitely need to put in place some sort of referencing effort that's bigger than the existing WikiProject, but if large existing unsourced articles that are otherwise not creating any problems are getting deleted if someone can't find the references in a specified time period, you're making Wikipedia worse, not better.
A lack of sources is only a real problem when the facts are dubious or questionable.
Lack of categorization is the worst reason to delete something I've seen. There is already a large organized effort to do this and someone can do it easily often without knowledge of the subject. Categories should be the easiest to add.
Mgm