First, welcome to the forums. You pose a great question. Let me see if I can give you a good answer. Verizon recently started a new data plan, by which the user can opt for either the $15 plan which offers 150mb/month or the $30 plan which has unlimited data each month. Before this, the user only could get the $30 unlimited plan. A data package plan is required for all 3G Smartphones. With that in mind, say you have the $15 plan. You are going to be frugal with your data minutes. With WiFi, you don't have to use your mobile device's data to perform tasks such as web browsing, email, and instant messaging. You can save a lot of money each month with the $15 plan, to be exact, save about $180 a year. If you have the Tour, you are probably better off with the unlimited plan. I have the Bold 9650 and it is a great device. You can tell by just the material used to make the Bold it is a quality device. I hope this answers your question about why you need WiFi.