I know this is an old thread but just my two cents. The best reason for me was when it came to switching. With a smart meter I have all my year's worth of data online and ready to hand: consumption, KWH used, cost, which month was the worst, what time.of day, etc. This makes is so much more easier to just do a proper price comparison online rather than guessing your usage.

Plus I don't have to send manual readings back to the energy company and there's nobody knocking on my door anymore to check up on me. Couldn't be happier.