Originally Posted by Zouf
Ah - cost vs price confusion. I guess you mean: ball bearing BBs are sold for more than the cost of taper bearings. If you are the manufacturer, it sure matters how much it costs - otherwise, Asia would be a place far far away, not a place where everything you buy is manufactured. Ball bearings cost less to produce than roller, and a lot less than taper; so that's what we have.
This being said, I'm not quite sure why you'd like to see tapers; as there is little lateral load on a BB, rollers can do great, for the same physical volume.
Eh... what?? Every cup-and-cone square taper bottom bracket I've ever seen used ball bearings. "Square taper" doesn't refer to the type of bearings, only to the form of the ends of the spindle, where the cranks attach to the bottom bracket.
The only reason that the spindle shape affects the choice of bearings is because a standard bottom bracket shell is about 1.37" wide; with a typical square taper spindle (about 3/8" in diameter I would guess) there is enough room to fit a bearing with 1/4" balls, but with a larger-diameter spindle the balls must be smaller. By moving the bearings outside the shell, they are no longer constrained by the 1.37" diameter...