[perihelions]

It's an engineering tradeoff of payload vs. booster cost. It's heavily one-sided for this launch—you get 4x more payload to this interplanetary orbit with the expendable Heavy vs. the reusable one [a].

Future launches with Starship, analogous to this one, would refuel their upper stage in orbit to their full capacity, so there would be no performance downside to recovering boosters; you would need more launches, but they would all be reusable.

[a] https://elvperf.ksc.nasa.gov/Pages/Query.aspx (I queried for a high-energy orbit with a C3 of 42 km^2/s^2, which I think is correct, or at least very close)

[whamlastxmas]

Also with starship launches only needing about a million dollars in fuel, it makes a ton of sense to just launch fuel to orbit versus sacrificing an entire ship