Because of all the posts about people having issues with them. Issues switching, display not working, readings connectivity not working, needing replacement meters quickly, etc. No need to let them experiment on you.
Then there's people who think they're fundamentally flawed because they add money to your bill and open you up to getting charged more at peak time further down the line and there was nothing wrong with dumb meters so complicating them just creates more ways for them to fail (same story as smart lightbulbs, smart doorbells, smart thermostats, etc.)