If I repsonded strongly to your statement it is partly because I was suprised you said it. It is not strange for me to run into thinking here in the US along those lines - except, unlike in your case, most people are dead serious when they say it. I have a hypothesis for why Africa always comes up in discussions about this with people in the US, but I won't go into it because I would think it wouldn't apply to you.
Anyhow, I see no reason why investing completely in nuclear coverage is more effective than dividing assets between several power types. I believe there are a couple of things you are not taking into account.
1) Is it safe to say you are from a country whose population is reasonbaly dense? Nuclear power is a fantastic solution to city energy supply. Nuclear power is a poor solution to rural areas energy supply. It is expensive to transport power.
Here in the US we have vast tracts of open land, and huge farm areas. In both of these, the size to effectiveness ratio is virtually meaningless; windmills placed on farmland can reduce the crop yield by tiny amounts, and increase the economic value of the farm considerably. It still isn't economic to do this on large scales, but we are getting close to reaching a time when it will be.
2) I believe you are only considering a single use for these alternative energy sources - that of electricity. Solar power especially has direct uses that do not require electricity, but save electricity and other recources. Wind qualifies too, but less so and in different ways. Take solar water heaters for instance; it has been shown they pay for themselves in warm areas, and are beginning to be sold regularly in the US. Why shouldn't we invest in them?
If you have a hard time imagining what the 250,000 nomadic people of Western Sahara would do with a lightbulb (which you shouldn't), maybe you can think of some use for a solar water purifier that can purify any water in a short time (even urine and many types of polluted water).
If renewable sources are so poor choices, then answer this: why has Japan seen a huge increase in solar power sales even as government funding has been phased to a fraction of what it once was? Why have solar cells seen huge increases in sales worldwide over the past decade? Why will thin film solar cells, which require a fraction of the materials, not end up highly efficient methods of extracting some energy?
You'll have to pardon me, I don't remember where you are from - Northern Europe? Currently, the facts seem to lean your way; solar power is just not as efficient a form of energy as other sources. However, being in Birmingham Alabama, things appear differently to me, and while the current facts lean your way, it would seem time may be on my side.
I believe that picking a fight with renewable energy sources only muddles your message.