[SkyMarshal]

Are you saying we shouldn't continuously improve our scientific systems just because one day we might need to rebase it on Martian or some other physical constants?

There are two aspects to the metric system - the physical constants that the base measurements are derived from, and the mathematical relationships between different measurement scales, from microscopic to macroscopic.

The latter aspect will remain useful and sensible even if we need to rebase the former on something more appropriate one day. But that day is a long way off, realistically a century or more. Not a great reason.