Question on fx surrounds

[begbie]

For the fx500i and similar models.
Any reason why they used two tweeters and one mid/bass driver vs. one tweeter and two mid/bass drivers ?
Are highs better dispersed? Is is really just cost?

[hoosier21]

High freq. is more directional than Low freq., so if you are designing a surround speaker line, and you are making smaller and smaller cabinets and price point, then I guess you can pull the second mid-woofer and leave the tweeter and still get a difussed sound field.