Is there any reason to define a 0-argument (read: zero-argument) macro with a starred command (
\newcommand* instead of
\DeclareRobustCommand* instead of
\DeclareRobustCommand)? After all, if there are no arguments, there is nothing to verify about them.
One reason to use a starred version could be consistency in the appearance of one's own LaTeX code. A reason against could be if starred variants are slower, but I don't know whether this is the case.
(This has nothing to do with the choice of starredness -
\somemacro* - which one is defining (and how to do the latter is btw not obvious, though it's definitely possible). This is about whether the definition of
\somemacro should be performed using a starred or unstarred defining command.)