With over 300 different technologies and upgrades, it is impossible to research all of them in a single game. Each technology is very useful in upgrading your state, as they improve aspects of your nation from the range of your artillery to the efficiency of your peasants. If a player does not use their technologies to their optimum level, or not at all, he/she will most definitely be defeated. Most technologies improve your nation dramatically. Sometimes one aspect is improved by 100% with just one upgrade, even by 200%. Technologies and upgrades are incredibly important, and the advance of a nation will stagnate if they are not used.