You can now buy vastly more computing power and do fancy fluid dynmaics, etc thanks to GPUs. 20 years ago it was much more expensive to procure, and much harder to find expertise. 30 years ago, I suppose, the field was even less mature, and limited to the few HPC installations and in-house bespoke software.

Mass-produced hardware drove prices down, and availability way up, in many industries: motors, analog electronics, computers, solar panels, lithium batteries, various sensors, etc. Maybe reusable rockets, enabled by all that, are going to follow a similar trajectory as air transportation.