But more recently consumers have had the benefit of a rare combination of benign factors that cannot be counted on to persist indefinitely.
One is overcapacity in generation.
Investment committed when projections were for demand to grow at about 2 per cent a year instead encountered recession and a flattening off of consumption.
The generators and the Government appear confident demand growth will resume, at something like the compound annual growth rate of 1.6 per cent a year which prevailed between 1990 and 2010.
But in the meantime there is no shortage of generating plant.
The recent severe cold snap, which coincided with half of Genesis Energy's 1000MW coal-fired plant at Huntly being off-line for maintenance, was accommodated without any evident problem.
A further factor is the risk of bottlenecks in the national grid which are reflected in high spot prices on one side and low prices on the other.
The vertically integrated generator/retailers want to avoid the situation where there is a grid constraint between their generation assets and their retail customers.
The reshuffling of assets among the state-owned generators has led to a scramble to acquire new customers near where their power stations are. Increasing retail competition in areas where it has been limited was, indeed, the point of that reshuffle.
The companies' recent results all cite heightened competition as a feature of the past trading year.
This is a one-off adjustment.
But expectations are that, even after the adjustment has played out in a year or so, the rate of customer churn will not fall back to the past's torpid levels.
In a recent report on the sector, analyst Grant Swanepoel of Deutsche Bank's sharebroking arm, Craigs Investment Partners, expects the current situation of over-supply to persist until 2014, even if one of Huntly's 250MW units is decommissioned as planned.
When it comes to potential new generation, the pipeline of projects in various stages of the consenting process equate to roughly half of current generating capacity.
And almost all of them, 85 per cent, rely on renewable sources for their energy - geothermal, wind or hydro.
Because the marginal producer is no longer reliant on fossil fuels, the forward cost curve for new generation is not linked to the outlook for gas and coal prices, or commodity markets more generally, as it is in Australia for example, Swanepoel says.
Nevertheless, as the cheapest options are developed first, the forward cost curve is inevitably a rising one.
Wholesale prices will have to rise to levels that make investment in new generation economic.
To get to the level required in 10 years' time, real price growth of 2.6 per cent per annum is needed, the Deutsche Bank report reckons.
"This means that somewhere over the next five years retail pricing needs to begin rising materially or the lights are likely to go out."
New Zealand electricity futures on the ASX market average $86 a megawatt hour over the coming year, $90 the following year and $92 the year after that.
Ralph Matthes of the Major Electricity Users Group objects to generators arguing that they need the near-term price curve to be at or above the long-run marginal cost (LRMC) of new generation before committing to undertake it.
"They are trying to pull the wool over the eyes of the public," he says.
"When MEUG members make capital-intensive investment decisions what matters is the long-term price and return over the life of the project. To get an immediate payback where revenue is greater than LRMC is rare."
Rare, and unnecessary so long as real prices on average over the life of the project are above the break-even level. "Waiting for the near-term price to go above LRMC could be fatal for a supplier, as other suppliers build generation and sew up customers with contracts."
Generators' scramble for new customers has been aided by the fact that the past three years have been "wet". That is, enough rain and snow have fallen in the catchments of the hydro lakes to keep storage above the long-term average.
An abundance of free fuel for the hydro generators naturally depresses wholesale prices.
But over the past month the situation has changed, with inflows running at about three-quarters of normal and storage levels close to 80 per cent of normal. Spot prices have risen in response.
The Deutsche Bank report says that over the past couple of years a growing proportion of commercial and industrial power users, who account for about 60 per cent of total consumption, have moved towards exposure to spot prices.
"The generators appear reluctant to drop [contract] prices while industrial, having become used to three years of modest wholesale prices, are not willing to pay up."
The controversial events of March 26, when spot prices spiked to around 300 times normal, ought to have burned off some of that risk appetite.
But the Electricity Authority over-rode those prices, the moral hazard notwithstanding.
It remains to be seen whether the High Court, which has been asked to overturn the regulator's rest of the market price, will take a different view.
Overall it seems, then, that happy days of this combination of oversupply, heightened retail competition and benign hydrology are numbered.
With luck it might last a year.
Then conditions switch from a good time for consumers to a good time for investors in power companies.
And on current polling, it looks like there will be plenty of them.
