When you give the government, on any level, the authority to do good things you necessarily give it the power to do bad things, either by intention or mistake. Constitutional limits on the power of the State exist not entirely because the State can be evil, but because the State is all too likely to be mistaken.
The Mayor of New York should not have the power to dictate how common beverages can be sold in the city. But the really worrying thing about his soda rules is not that he thinks he has that power, but that he has been elected three times. The problem is that he should not matter that much. He should not have the authority to make so many stupid rules. By allowing so much of the Constitution and the Bill of rights to become a dead letter, we have allowed all kinds of meddlers to invest the State with power it should not have. They may be doing this with the best of intentions, but they are not as smart as they think they are, and the consequences of their various obsessions are not universally, or even mostly, good.
All kinds of people think that they should be running things. The vast majority of them are wrong; a majority vast enough to justify making sure that none of them ever get the chance. Government authority should be small enough that misuse of it by a monomaniacal nitwit would not matter.