Sorry. I don't talk about fundamental operation system design. I don't want the symbian one. Because of this I moved to maemo.
I'm talking about such things like Devices with Touchscreen that unlocks itself in the pocket and no autoexposure lock on half-press of camera button.

They desinged it like they want and begin to think about it from the early beginning without looking how this works on other Devices. Nokia has many experience with mobile phones. Why not ask before do the same mistakes again?

Nokia had the same unlock problem at the Nokia 5800 and as far as I know at their N97. They finetuned a lot at the proximity sensor of the 5800 and in the end they gave up and implemented slide to answer as every other manufacturer does. But before they fixed it they said a long time "it works just fine, you are to stupid to use it" - and now we got THE SAME discussion on the N900 again and frighteningly also the finetuning at the proximity sensor.

The sensor works fine to lock the device during the call. For this it is designed. For this it works as expected. But it doesn't work when you have to pull it somewhere out to answer a call.

And for the autoexposure lock I linked above, the programmer has obviously no experience using a normal camera or at exampe a Nokia N95. No problem at all! But when he doesn't know he should ask one from the symbian team or test it before how it should work.