Ukraine

It seems to me that the drones they're using to huge effect have proven very effective at piecemeal strikes that chip away at the enemy one ship at a time, at very low cost in both manpower and money.

Drones cannot at present replace manned vessels in conducting long-time operations or area control. Stuff like continually patrolling and protecting offshore installations, preventing the enemy from laying minefields, or escorting convoys are still stuff you need manned surface vessels for.

Whether those tasks are something the Ukrainian navy should be prioritising at the moment is a fair discussion to have though. Two corvettes is likely still short of what is needed to contest general control of the Black Sea, even against Russias crippled Black Sea fleet.