I think HVDC is a more important component in smoothing out demand/supply than you give it credit for, especially if you add wind into the mix.
In terms of security - one of the reasons nuclear power stations are so expensive is they have to survive a targeted plane crash etc - they are expensive high profile targets.
In the end the renewables model is a much more distributed model of generation, storage and consumption ( rather than a few massive power stations ) - so with a proper grid you could argue you would have fewer single points of failure, and increased resilence.
Nuclear power plants are not expensive per unit of power delivered.
"distributed" sounds good as long as you don't think about it too much, because that distribution does not actually buy you decorellation: all these "distributed" plants produce very much in lockstep due to external factors (day/night, weather, seasons) that are extremely correlated, much more than any set of nuclear power plants ever could be.
Intermittent renewables do not increase resilience, they massively reduce resilience. In Germany, redispatch has increased more than tenfold in order to keep the grid stable in light of the destabilizing influence of intermittents that have been introduced. Spain just suffered their blackout last year with over a hundred deaths due to this destabilization (though the PR is trying everything to deflect the blame).