The issue is that planetary locales will each have their own days and years (and possibly hours), so it would be confusing to adopt that same nomenclature for an interplanetary/interstellar time unit. And since the latter will be inconsistent with local time systems anyway, it’s easier to just have it use powers of ten. At least until we meet aliens that may prefer a different base.

But this makes no sense, humans can't just change their circadian rhythm to match an arbitrary daylight cycle, and clocks aren't necessarily reconfigurable. And with a good enough artificial lighting you don't need to depend on star. Daylight is just weather, it has nothing to do with how calendar works.

I was 100% thinking of use by humans living on other worlds. Pretty sure Mars will use seconds and hours. Handling dates will awkward whatever they decide on.

Currently, a Mars days is called "sol", FWIW.

If we find other species out there I won't speculate on how they think about time.