I agree with you in my heart, but I'm worried we both could be overlooking something important, so let me steel-man an argument against:

You said correctly that the private utility monopolist can choose from the menu of raising prices, delivering a subpar (cheaper) service for the same price, or can "defer" (aka skip) maintenance indefinitely. All ways they can extract cash to pay shareholders or even worse, pay management fees to private equity.

But the government-owned utility that we idealize, which provides the reasonable service at a breakeven price, may not be realistic. Government has its own incentives: Some politicians want to take funding from your utility to pay for their pet project. Others (political operatives or even civil servants) may sneak in a corrupt overpriced contract to benefit their corrupt associates. Public unions are known for negotiating unreasonable work rules and contracts that preserve jobs that are not actually needed.

All of the above together create a drain on finances of a government-owned utility, which is the public counterpart of the drain on finances that "the need to make a profit for the owners" places on investor-owned utilities.

I hate my local investor-owned utilities with a fiery passion and can't believe most governments could do worse, but I think we shouldn't overlook how easy it is for nationalized entities to engage in similar amounts of shenanigans.