Apple has a netbook - its called the iPhone. I use my iPhone like I would use a netbook and then some.
I reach for my iPhone (and it's not a long reach, since it's always in my pocket) for >80% of the things for which I used to reach for my MacBook. I have essentially zero desire for a netbook because of it. (Yes, yes, I know that's not the case for everyone. But I can't imagine a usage in my life where either my iPhone or my MacBook isn't a far better fit than a netbook.)
A netbook or tablet+bluetooth keyboard OTOH would be a little more handy for that. Not saying it would be enough for me to buy one, just an observation.
So you can install any software you want on it?
The fact is, I can install a large number of applications on my iPhone, the device is readily available, and has a great web experience.
The point of a netbook in the first place is to be able to access the web, and be able to quickly get at the web - not to be able to install all applications.