You are missing the point. Cities do not exist because people simply vote to create them. The vote to create the city and the authority to hold the people to it comes from the state. The state controls state laws for all people and what the cities may control. Cities are not anarchical entities that operate without state oversight. Cities are located within the state and are subject to state law.
So then, you're in favor of the federal government being able to overrule state laws?
That's the next step in your logic - states aren't states until they're recognized as such by the Feds, after all.
If voters want marijuana legal at the local level, than the local LEOs should step aside. Let the State Police expend time and resources to thwart the will of the local voters.
Horse vomit. Then why are all these cities enacting smoking bans without the state's permission then?
Cities and municipalities are sovereign entities just like states are (supposedly) sovereign from the feds.
It is more than that. The Constitution of the USA recognizes 3 entities: The People, Federal Gov't and States. Cities, Counties, Parishes, etc. are administrative constructs and subject to the wills and whims of the state within which they were created. State law trumps local law, period. It can't even go to SCOTUS because there are no Constitutional issues.