The main disadvantage with expose is not loosing the agility but loosing the action instead. Along with taking up that valuable EPT slot.
Sure expose is better on the VT-49 than any other ship but that doesn't make it the best upgrade for the VT-49.
Which is why it is only run with Experimental Interface, trading the action cost for a stress cost. With Admiral Cheerios you get a focus effect for free and toss in a weapon engineer, I have actually had many turns when I didn't really need to take an action in the Perform action step at all. (I did of course, there is always the possibility of rolling more than 1 eyeball).
So yes, that expose costs you an action is very significant, but on a decimator it is hardly an insurmountable problem.