Just to briefly open this up; the design dogma in regards of class powers has been that reliance on others should be highly desirable in order to have a good chance against the challenges of your appropriate level.
A lot of balance changes have been done partially due to this motivation. For example, lowered summon durations, death system for familiars, unstacking of Acid Sheath + Death Armor + Elemental Shield and the decreasing of power of various buffs such as Polymorph Self, Divine Power and Divine Favor.
From my view, allowing familiars to be polymorphed would be in counter to this approach.
There is still an use for summons. Especially at lower levels, a well-placed Dire Wolf can be a big asset with a few simple buffs laid on it. At mid and high levels, a buffed-up summon is still at least a great distraction in tough spots. The meat and butter of toe-on-toe combat does lay on the PC warriors, though.
EDIT: Moved the topic from Bug section.
