Sure, you'd have to engineer it correctly and this would not be cheap. But in the context of all the other things you'd have to spend money on to do a successfu

Sure, you'd have to engineer it correctly and this would not be cheap. But in the context of all the other things you'd have to spend money on to do a successful Mars mission, it IS trivial. Artificial gravity can be as simple as putting your habitat at the end of a tether, with a counterweight (say your Mars injection stage) at the other end. That's about 1/100th the complexity of the Sky Crane manoeuvre that NASA just pulled off, and certainly nowhere near being one the "top 5" engineering challenges. Unfortunately, the approach for the last several decades has been to say "gosh, microgravity is scary, maybe we can RE-ENGINEER THE HUMAN BODY to can cope with it". That's a canard. Spam in a can at the end of a string is trivial in comparison.