Too short election terms make for a dysfunctional government. With the usual 4-5 years most countries use half of that term is already spent campaigning for the next, forcing the government to do anything unpopular (but often necessary) during the first years, and then tone it down and do popular things else they have no chance of getting re elected.

If you shortened that further the politicians would be forced into a perpetual state of pandering to the voter base instead of actually governing.