@Modulok: I believe "Hanlon's razor" applies here: "Never attribute to malice that which can be adequately explained by stupidity." Nokia's forking from Debian is probably just an unfortunate result of Debian not having an armel port when Nokia started with ITOS, and a simple case of software diverging over time.
As someone who was previously tasked with getting Debian to fit in a 512MB flash drive for work (web kiosks) I can tell you that it is very, very easy to start diverging from your upstream distro when space becomes a problem. Fitting Maemo in 128MB of flash is quite an incredible feat, and obviously sacrifices were required along the way. I can tell you right now that my minimally functional Debian requires 550MB+ of flash. This can be reduced but it will never fit in the onboard NAND. Also, Debian is definitely using more memory than ITOS. This can be reduced but probably not solved entirely without making it something else besides Debian...
Also, I really do trust at least the Maemo team not to actively screw us over. They're not out to get you! Nokia as a whole probably doesn't care about us enough to be even bothering to use bait and switch tactics against us...
That being said, it *is* important not to be stuck in a "vendor lock-in" situation. But, let's concentrate on doing something productive rather than speculating on what Nokia might or might not be trying to accomplish.