[gevatter Lars]

Maybe production cost?
I would guess that creating a air/space craft is more complicated then building a ship that has to be good in either air or space combat.

[Aginor]

What Lars said.

But another reason: Those are still Kilrathi, they often don't trust each other. So if you give them atmo-only fighters it is less likely that they suddenly overrun your space forces. You can control that planet better.

Just a thought, I stick to Lars' explanation, it is the most obvious one.

[Arrow]

I always thought, a pure atmospheric fighter should be able to out-maneuver a pure space fighter in the atmosphere quite easily,  because it was designed to stick to the rules of aerodynamics in the first place.  Mass and uplift are essential here while a space fighter is a brick in comparison because it was never built to keep itself in any air...   
The Ekapshi though, is a very bad example for an aircraft... I doubt, some RC model build with that shape would even fly at all!

[starlord]

does saga have an ekapshi model?

[Damage]

Just downloaded and watched the trailer--I know I'm in trouble when I catch myself leaning to one side in an attempt to actually see around the objects on my screen.  Awesome eye-candy!