Why is is unambiguously good? There's great reason to doubt it could be anywhere close to economically competitive. That makes its value pretty ambiguous, in my view.
Well designed fusion power should come in at or below hydro-electric power without the environmental impacts or risks associated with dams.
> ARC is a 270 MWe tokamak reactor with a major radius of 3.3 m, a minor radius of 1.1 m, and an on-axis magnetic field of 9.2 T.[2]
> The design point has a fusion energy gain factor Qp ≈ 13.6
So the reactor is about 25-30 feet in diameter, plus the steam plant / FLibE processing.
Have you seen the size of a nuclear cooling tower?
That's what fusion aims to solve. The fuel is plentiful and you can easily buy it; the same can't be said of uranium. It's also much safer to run than fission, and produces vastly less dangerous waste.
Perhaps your argument is that solar and wind are sufficient to power humanity's needs, without fission or fusion. That's debatable. But compared to fission, fusion is theoretically better on some pretty critical metrics — if we knew how to build a fusion reactor, which we don't yet. If you assume solar and wind won't be sufficient, fusion seems worth research.
This is nonsense. You can't ignore the cost of building plants, when trying to determine if a technology is competitive. Nuclear plants have to be paid for; they're not given to us free by the Nuclear Fairy. If you include capital and financing costs, you will find they contribute more to the cost of energy from the plants than do operating costs.
You're missing one important part: the reactor must be profitable enough so that it can recoup the build cost for its lifespan. The lifespan of fusion reactors, even disregarding failure modes, will be severely limited by the high energy neutrons which it generates, and which turn all materials brittle.
And maintenance for the brittle material will mean stopping the reactor, and sending in robots to dismantle and carry away the brittle radioactive walls, and build new walls in place. It may well be about as cheap to scrap it for parts (for those parts that haven't been turned to radioactive Swiss cheese) and build a new one.
Generators are coupled to this thermal storage. When wind and sun is good, there is a continuous build up of heat stored in molten salt by fusion reactor. When it is low, net heat gets drained from molten salt storage to power steam generators.
Fusion, like fission, is a high fixed cost, low variable cost power source. The cost of energy from such a source escalates rapidly as capacity factor goes down. They are very poorly suited as backup sources for intermittent use. Hydrogen (made by electrolysis from renewables and stored underground, then burned in $400/kW turbine power plants) would be much cheaper as a backup source.
The reality of energy today is we basically have the technology to cleanly power the human race for the rest of it's existence - politics and tribalism is why we can't.
The energy density of fusion is inferior to fission, when you take the mass of the reactor into account (as you must, if you are worrying about the mass of your system.)