As for others who do only come out and write during these months, so what? I've been working steadily on projects for a few years now, but I certainly know what it's like to be in a rut, and if NaPoWriMo can be the catalyst for increased productivity, all the better. Hell, it's great when it gets virtual non-writers to adopt the craft. More writers, more poems. And I don't necessarily subscribe to the theory that that's a good thing...but you know, poetry is vastly under-appreciated, and it really can take just one person's verse to inspire someone else to dive further into the medium. It doesn't have to be solely about quantity over quality, either; you can achieve both by building some mental notes and ideas beforehand, as well as making tentative plans for the project's destination afterward.
That is all, getting off the soapbox, now.