I disagree. Humans in general may be bad at deciding what benefits from inlining, but runtime library implementors can be presumed to be skilled, have thought hard, and (hopefully) tested the alternatives.

In this case, I have thought hard, and deduced that inlining this method will always result in a single call to make() with the same or fewer arguments than the inlined call to make-sequence(). This depends purely on the presence or absence of optional arguments, which is guaranteed to be decidable at compile time.

Thus inlining, as well as making faster code in every case, makes smaller code in some cases and larger code in no cases.