I guess he main reason used to be agriculture. We need to monitor the weather to be able to predict it. Farmers need to know what the weather is going to be like so that they know when to do things like harvesting the crops. I am sure that is still important, but these days most of us are not farmers. I like to know what the weather is going to be like so that know if I am going to need my waterproof cycling clothes or if I should buy barbecue food for the weekend, for example.