@sheikah attackers also can have bonuses from it
for now the attacking player have a longer delay in supply (his factories is far away), so it's quite hard to hold captured territory
but if for example t2 com can pretty fast repair all damaged units it will be easier to hold this territory and then attack once again
also attacker's units might already have veterancy so when they will be full hp - they will be stronger than equal enemy army, that's really intresting
Overall, nothing changes: do not fight the battle you cannot win
But a win in battle will be more rewarding (because your survived army will be stronger than before, after repair)