That, and it cost more (even if it was included in the TV at no cost, they'd usually nail you for the price of the glasses). It's really just about the only format change where we've been charged an extra premium at all angles and every step of the way, whether the cost is defensible or not.
Probably because ghosting was a massive problem during the early days of 3D at home, and many displays by a multitude of brands had difficulty displaying a great number of titles whenever there was anything more than moderate depth or pop-out.