Is necessity really the mother of invention??

During my trip to India I read the book "Guns, Germs and Steel". A very interesting book which analyzes why it was europeans who conquered the whole world rather than the other way around. One of the most interesting arguements in the book was about how inventions are more due to environment rather than just the random genious of a person. Also how there have been many inventions which actually were not made for the specific purposes they are used now a days.(steam engines were not made because all of a sudden rail transport became necessary!!) For example we always learn about how Edison invented incadescent lamp but do you know there were 18 patents on it already. Not taking any thing away from Edison, he made a tiny improvement. The time of invention is very important. When Edison invented it in US electricity distribution was also just picking up hence his invention became a house hold thing. Hence they quickly found a use for it rahter than some necessity leading to the invention. I saw a immediate parallel in the market of online search engines. There was a search engine before google came but at that time net itself was not big enough to support such things. Later google came and we know what it has done to us. So big inventions are actually small additions to existing systems and somehow find a ready application. This process is fecilitated by good communication among competition which happened to be "just right" in europe during the 17-19th century.

Interestingly there are examples when very big inventions died out because there were no use quickly found for them. The most surprising casuality happens to be "writting". Writting came into Roman civilization and became extinct because they apparantely found no use for it. :) It had to be invented again :)). Also the earliest printing press excavated was from some BC. Though it was a very primitive one used to print on the tablets but still the idea was right. But it again died down because writting and reading was prevelant among a select top tier of society and it was mostly used to keeping records and hence no need for many copies.