I like a small group that I can equip & that will carry out orders in combat - not least because I will sometimes wish to retreat and nothing is worse at such times than suicidal minions.
A pet is like the poor cousin of a party member: no personality or equipment needed, and never adds anything to the story.
Perhaps DD2 can change that <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" /> ?