> Would we have more advanced rockets
We wouldn't need rockets at all, or at least far less; we could power things like launch loops and railguns to get things into space (and then either settle for rockets to circularize or else use laser ablation or orbital tethers or other fancier systems to circularize).
> or robots or phones? Better CPUs?
Robots, phones, and CPUs all benefit from power being readily available. For the latter-two, power storage is a critical factor as well, but it's at least a little bit less critical when there are ample places to cheaply recharge.
> More and cheaper housing built in dense cities?
Dense housing tends to require things like elevators (unless you expect people to climb tens or hundreds of flights of stairs every day), climate control (in places naturally too hot or too cold for humans to safely live), and the very equipment and materials to construct that housing in the first place (cranes and bulldozers don't run on magic, and neither do steel mills or window factories). Not to mention the things people like to be able to do within those homes, the vast majority of which require electricity. Cheaper electricity makes these things cheaper.
> Cheaper education or medicine?
Electricity is typically required for distance education and telehealth. It's also typically required for modern education and medicine, period. Cheaper electricity makes these things cheaper.
> More job security?
Not only does energy itself tend to create jobs (especially solar, what with all the rooftops and parking lots begging to be made useful with solar panels), but so does the resulting burst in commercial and industrial opportunities when people are able to drive down or outright eliminate electricity's cost to business.
> Even more food?
Vertical farming at scale will absolutely require more electricity. So will water production; desalination is typically an energy-intensive process, but with enough energy production, it could make water shortages in places like California a thing of the past. Even traditional/flat farms have tractors and combines and other equipment that are costly to run; slash those run costs, and farming just got that much more viable for smaller farmers that can't otherwise foot the bill.
> I don't really think we're constrained by it (or by manufacturing in general) right now...
Right now the energy and manufacturing capacity we have is built on egregious exploitation of fossil fuels, particularly coal and oil. Those won't last forever; either they'll run out, or we'll end up wiping ourselves out with the resulting greenhouse gases (or probably both).