The strength
of composites depends on the direction of the lay-up of the fibres, so it is
not necessarily the same in all directions. In fact, the advantage of
composites is that you can tailor the material to give greatest strength in the
direction of greatest stress
The whole point of development in materials is to get
a GREATER strength/weight ratio.
And, finally, it depends on what you mean by "same in all
directions". I doubt you could design a structure that gave the same
bending flexing tension or compression responses in all axes. (Actually, what about a solid sphere?)