Question on utility statements and parameterization

Hi all;

As I understand, utility statements are not generally parameterized, so:

postgres=# alter user test123 with password 'foo' valid until now() +
'1 day'::interval;
ERROR:  syntax error at or near "now"
LINE 1: ...lter user test123 with password 'foo' valid until now() + '1...

Is this by design?  If so, what is the reason?  If not, what would
have to be done to change this?

Best Wishes,
Chris Travers