Well, one can presume that, or one can wonder if Delta was seeing some market share erosion and/or loss of coach pricing power, and felt it needed to respond in more city pairs. Marketing more E fares could be defensive rather than an indication that it's doing well.

As a DL shareholder, I am actually a bit concerned that E fares may erode Delta's coach margins. Frontier is reducing Denver flying, I haven't looked yet to see where they are increasing capacity, but they are an E fare competitor.

Airline marketing is not my deal, but as an industry watcher/sector investor as well as a traveller (and DL FO), I had hoped that Delta was going to try and be above the Spirit/ULCC fray. I don't think it bodes well for quality of travel over the mid term.

edit: I am also not a corporate traveller, but I think they have a substantive problem on their hands for PMs/DMs who's companies force them to buy lowest fare. Technically that's an employer issue, but it gives an AAdvantage to other airlines, UnLess they follow Deltas E fare race for the bottom.