Yeah, I tend to agree with most of what MrJayVee writes in his blog. A short film isn't a magic spell that'll catapult you into fame and fortune. Also, yes, most short films suck. It's because they're easy to make, and with digital video and all kinds of cheap editing software and Internet video platforms, there are more shorts out there than anybody could watch, most of them made by people who are struggling to learn the basics of filmmaking. Some of them will move on to bigger and better things, many of them won't.
But hey, that doesn't mean you shouldn't do it. I do believe that experience is important. Any kind of experience. Your stories will be better, your dialogue will improve, and you'll know more about the process of filmmaking. And networking is important, too, and while the people making the film are hoping to break in just as much as you do, they may be in a completely different place two years from now, where other opportunities may arise. In many cases, it won't happen, but you'll still have the experience.
Keep in mind, though, that America and Europe are somewhat different when it comes to filmmaking. European budgets are usually much smaller, and deferred payments (or partially deferred payments) are much more common. That means that a lot of newcomers try to start their own feature film projects, backed by film board funding and kept relatively inexpensive with deferred payments. Some of those projects involve people who've worked together on short films, and some of those projects find a distributor, helping the people involved to get bigger projects off the ground. So, yeah, short films may make more sense in Europe than in the US, and yes, they may also make much more sense when you're also the director.