Yeah, I know. Doubling or tripling their subscription rates was a total and complete failure.
I would be extremely surprised if more than a tiny number of people subscribe for the e-mags. For the most part, it will be the Character Builder and Compendium, with the DM tools (or is it just Monster Builder these days?) coming third. At best, I'd bet the e-mags are a nice-to-have.
Meanwhile, cancelling the magazines led directly to the creation of Pathfinder. At a stroke, WotC turned their biggest cheerleaders into their strongest competitors. And, because almost all existing subscribers were offered at least a few issues of Pathfinder 'free', and a great many of those subscribers took up that offer, Paizo were able to convert the Dragon/Dungeon subscriber base into the core of their customer base.
Every month, I used to look forward to the arrival of the two magazines. Even when I wasn't actively playing, it was a drop of new stuff, a means to stay connected to the community, and then something to come here and talk about (at some length). And it wasn't even the game content that was important (other than the "Shacked City" campaign, and a handful of other adventures, I never
used any of it), but the fact that it was present... that was important.
And now, every month, I look forward to the arrival of my Pathfinder instead. I get it every month, I read it every month, and I enjoy it every month. And yet, I've
never played Pathfinder. Where my loyalty was to D&D, now it is to Pathfinder (and Paizo), and that's because the magazines were cancelled.
(And, worst of all, if WotC had simply renewed the license and let Paizo continue, it's quite likely the magazines would have failed by now. The market genuinely was contracting, and if it had been WotC publishing them, the time to stop was indeed right. But it
wasn't WotC publishing them, it was
Paizo doing so, and taking all the risk. So... no Pathfinder, much stronger support for 4e, and then the demise of a licensee/competitor. And all WotC would have had to do is... nothing.)
Failing to renew that license was probably the single biggest mistake WotC (well, the D&D team) have made since 3.5e was published early.
Edit: But, of course, hindsight is always 20:20. There's no possible way WotC could have foreseen what has actually happened.