Actually, communities tend to run infrastructure remarkably well. Look at water systems. When is the last time you were in a location with city water, turned on the tap, and nothing came out? (Assuming you weren't cut off for lack of payment, of course.) Towns know how to keep the water flowing. If a town is without water for a period of time, it makes national news. (Yes, there are developing nations that do not have potable water coming out of their taps. The US is not one of those nations, and this is a US topic.)
Governments are not incapable of running such a program, and they are not inherently guaranteed to suck at it.
Now, is this different because it will require tech support? Sure. Are cities prepared to deal with the calls, the service interruptions, the network attacks, etc? The cities that are asking are going into this eyes wide open. The FCC is not mandating that cities must carry their own networks, they are simply being asked to rule on a non-competition clause that unfairly prevents the city itself from providing said competition.
I think the biggest problem the cable companies face is that cities now know exactly how much it costs to run a network, and it's nothing like the extortionate rates the cable companies are charging today. If the city has a competent manager leading the project, and good engineering staff, they will deliver fast data along with great customer service at a price that is not only going to be competitive, it's going to dominate. Everyone wins, except for the shareholders of the cable companies - and as they've been winning for a couple of decades already, my sympathy for their plight is not exactly overwhelming.