In a perfect reality I agree. In our reality you often end up with a crappy unreliable or data volume capped internet connection. The data in the cloud is useless when I can't access it fast enough.
If the cpu is slow it just is slow. Lukas, if you want to spend your time waiting for the compiler rather than writing code, you can do that but I don't.
3. screen size
It is possible to run eclipse on a 1024x600 netbook. But I'm pretty sure the productivity is higher if you can fit an ide, one or two pdfs, a web browser and instant messages on your screen.
For example, I largely mitigate most of your issues when using my netbook by treating it as a terminal. The "real work" gets done on my faster rig, with compilation offloaded to a grid. Because of that, I'm only a tiny bit less productive on my netbook compared to working from my office.
And that entire productivity drop is due to the small screen.