Its about experience building
People who want to leap to Mars ignore them all. There is a huge difference between testing systems in LEO and Earth rather then on the Moon.
Lack of dust is one. And if the lunar dust is worst so much the better. YOU want your test environment to be worst then the real one.
The cost will be a bargin is it reduces the chances of the first Mars mission resulting in dead astronauts and a retreat from space flight.
Also the trust you put in computer simulations and Earth analogs tells me you must be a very young engineer not yet harden by the realities of actually working in extreme environments. Its amazing how far you believe a little bit of lab testing will go.