...snip...
In so many ways non-discarding ordnance effectively becomes a cannon in a different upgrade slot. It may have some other cost associated with using it but that is what it would be.
And that's exactly what I'm afraid of. the discarding is what makes torpedoes and missiles unique and separates them from cannons thematically and mechanically. They need to feel different or whats the point?
When ordnance, for the most part, requires a TL on the target it is to be used against that is enough to differentiate it from cannons for me.
Aside from the outrageous cost how would non-discarding ordnance be all that different from loading up a TIE Bomber and giving it Munitions Failsafe just for good measure?