Here are the reasons why I finally decided to begin one:
1) I want to give informations to newbies. I often saw recurring questions on the programming forums and I beleive these recurring questions should be answered in a sticky thread. This is not really feasible. Anyway, I'd like to centralize these recurring questions and answers in a non official FAQ.
2) there is no such thing as point 2.
3) I want to speak of my projects. To give informations about my code. To share my coding experience with gd.net users. Gamedev is really a great place, with tons of great individuals. Because I really like this place, I want to give a contribution to all the gamedev users.
4) I want to the master of the world.
Of course, I don't encourage anyone to read this devlog. I hope to fill it with interesting stuff/ideas/infos, and I hope I'll be able to update it on a regular basis. But if I spend too much time playing with it, I won't be able to master this world.
Mastering the world needs some time, you know...