One story a month though is not so bad - that's my second reaction.
I much prefer the idea of the Bootstrapped, Profitable and Proud series, which seems to be on indefinite hiatus. That being said, it should be interesting.
I would guess (?) that they're aiming for a medium in between those two extremes. But even still, bandwidth can be an issue. If you're doing primary discovery, primary research, and primary analysis, you're going to have to commit significant effort to produce something really good every month.
In general, we as readers tend to underestimate (and undervalue) the effort involved in primary research and investigation. Some of what we read in feature-length magazine articles involved hundreds of hours of primary research or experience.
It will make an even bigger name from them outside of the "core" startup community... can piggyback off any big brands, directly from their own, as all they need to do is call someone and say "hey, we're from Basecamp" since so many people love them.
(Not complaining here BTW, I'm pretty sure these will be awesome and inspiring stories I'll benefit from. It's just weird.)
"However, because we've released so many products over the years, we've become a bit scattered, a bit diluted. Nobody does their best work when they're spread too thin. We certainly don't. We do our best work when we're all focused on one thing." "Moving forward, we will be a one product company. That product will be Basecamp. Our entire company will rally around Basecamp."