Actually, most magazine readers no longer differentiate where they get their information from. The advertising and editorial are of equal service to them. This is especially true for fashion and lifestyle magazines. The days of church/state separation between advertising and editorial are basically gone.
Legally (postal rules) a magazine must be at least 20% editorial to be mailed under periodical postage regulations. Most magazines maximize their ad/edit ratio in order to maximize profits and the expense of paper and distribution. Subscription income hardly covers the basic overhead. My assumption is that only advertisers who pay are going into the digital version, and they are replicating only the parts of the magazine for which they have digital rights. So no matter how you slice it, the digital version will never be the same content as the print. That's why they need to reinvent the entire experience.
The fact is that editorial departments are not set up to provide continuous digital content, especially rich media experiences. Creating a monthly event digitally will be a problem for any magazine which goes onto the iPad. This is why the majority of success lays in opinion and news formats.