This may be too complicated for the fast-play feel of Forces, but what I would like to see is the ability to designate a certain unit as "mission critical".  Being marked as mission critical would make this the last unit chosen as a casualty, regardless of unit cost.  Some good effects of this feature:

• You could designate a single Troop in your attack as mission critical, so that if your attack barely succeeds, you still have a land unit to perform the territory capture.  (Planes can't capture, you'll have noticed, but they are destroyed last since they are most expensive).   
• You could mark your transports as mission critical, so that escort units and even planes are destroyed before your precious loaded transports.  (Making transports with cargo count as their own value plus the value of their cargo would have a similar effect, and would make sense)

Again, this may be outside the level of detail desired for Forces, but I thought it worth bringing up.