Inconsistency over point motion between mark-* commands

[Chong Yidong]

C-M-SPC (mark-sexp) sets the mark at the end of the current sexp,
without moving point.  C-M-h (mark-defun) sets the mark at the end of
the current defun, and moves point to the beginning of the defun.

Similarly, mark-page, mark-paragraph, and mark-whole-buffer all move
point; mark-word does not move point.

mark-end-of-sentence does not move point, which is appropriate
considering its name.

Does anyone know if there is a rationale for this inconsistency?