In the Dune universe, when a laser weapons hits a shield, both are destroyed in a nuclear explosion reaction.
So instead of building nuclear weapons, wouldn’t it be easier to tie a timer and a “parachute” to a laser gun and drop it from orbit onto your enemy’s city?
Well in addition to the other answers, out of universe, the answer is power of plot. Simply nuking the shit out of everything wouldn’t really make for an interesting story.
Right? Magic is real in Dune, we don’t don’t need a hard sci fi reason for every missing technology frank Herbert didn’t think of in 1965.
For the fun of hard sci fi is theorizing the stupidly powerful shit. Playing with the in universe science.
In any case they wouldn’t even need to have parachutes, just fire the laser a moment before impact or build some kind of drone that had multiple lasers that fired simultaneously…. Big, big booms.
Nukes play a rather pivotal role in Herbert’s book though. He definitely thought of them.
I am talking about OP’s idea of using lasers instead Nukes, nukes are fine, they fit the theme of 50s/60s geopolitical allegories rather perfectly. Using hard sci fi logic on a space opera sounds like an exercise in insanity, but OP is free to drive themself mad however they like. It’s Lemmy, we’re all mad in one way or another.
It did for the Killing Star. Not nukes, but R-bombs which are probably the most insane WMD-s and unlike strangelet bombs actually feasible even at our current tech level. All you need is a light-sail and a big-ass solar-powered laser.
But, yeah, for dune: