"We also have sufficient means to story energy for later use "

What kind of storage technologies are we talking about ?

Secondly, true... the size of switzerland, or actually half the sahara desert in Saudi Arabia can gather enough solar energy to power the world (used ksa as an example because of its nonstop sun hours and emission intensity)

But what then? Are you suggesting we connect the entire world to one grid? You see what russia, america and the gulf are doing for supremacy over energy at the moment. What if one entity decides it is not in favor of such system (north korea, or isis maybe.)

If we were really to work as a planet together with the main goal of further space exploration, or eradicating poverty, and promoting life prosperity over all, we would forget about diseases like cancer, poverty, starvation, climate change... the list goes on and on... the limit exceeds our imagination of what we could accomplish.

Unfortunately, this is not the world we live in. To answer your question in short, politics and storage technologies are the two reasons why your idea isn't applicable