Science

Studies like these use 'simulated Martian regolith' not only because we don't have the real stuff but also because the real stuff has lots of perchlorates in it (approx 0.5% by mass). And perchlorates are toxic to humans and plants at those levels. So "removing perchlorates from regolith at industrial scale, quickly enough, all the way over there on the surface of Mars" is a problem to solve before you worry about what/how to plant your first crops in it. Also the whole "greenhouses like they will use on Mars" thing is assuming/ignoring a ton, but I shall not digress on that further...

Knowing more about how best to use intercropping is important, yes, and a hell of a lot more relevant to humans here on Earth than some pie in the sky supposed long term residents of Mars some day. But that framing is sexier, so probably gets more attention, funding, or clout. Kind of like how all basic science research in cell and molecular biology is framed as being important for cancer even when it is more relevant to other things or just interesting for its own sake.