So many ways. The current paradigm is that it gets one chance and it has to be perfect. Starship (which I'm only referencing as the bleeding-edge launch vehicle) compared to Ariane 5 could be a fraction of half the cost, with double the volume and 4x the mass. With those constraints removed the science missions had a lot more flexibility in their design.

JWST cost $10B. The launch was expensive at $1.5B; but getting that down to $750M won’t really change the availability.

I'm a firm believer that if the mass and volume constraints were relaxed the design of such an instrument could be greatly simplified.

Hmm, I didn’t consider that, very good point. With 10x the volume, maybe the mirror and sunshine origami could have been avoided or much simpler. I wonder how to figure out how much the cost was because of that complicated mechanics…

The Europa Clipper mission saved $3B+ just by switching from SLS to Falcon Heavy.