Anytime you make something distance based it adds dimension to gameplay.

If you just FS'd, change your mind and want to play, you could recall fs without paying as huge a cost. some might not like making fs easier and more convenient. fsing is hard enough.

this avoids the issue of mislaunches where you screw up a big launch and have to recall and try again. opinions will differ on this. you can still have a minimum deut cost even for recalled mission.

The common explanation for 100% deuterium consumption upon recall is that 50% are consumpted upon start and 50% to accelerate when turning and flying back.