Why do magazines still have "issues"

This is something I ended up writing about briefly in my paper, and though tit was interesting enough to share here as well.  I was thinking about an example of a magazine that failed in print but successfully transitioned entirely to the web (I saw someone's post in drafts that looks like it's about the same site: Cracked.com).  Of the many things I noticed that they do now that a traditional magazine would not have done, I noticed that they update the articles and change their front page on a daily basis as new content becomes available, posting a handful of new items at a time.  Traditional magazines tended to load their issues up with a lot more content than this, because they had to pay printing and distributing costs and it's frankly more practical to do that all at once.  But these reasons don't apply to the web, and with our increasingly shortening attention spans we are less likely to read all of 100 articles published at once monthly than we are to read 4 articles published daily. 

Now, this doesn't apply to Din because it's only in operation during the course of a single semester and has different staff for every issue, but it's something for other magazines making the switch to consider.