^This. It's more about messaging than military advantage. NATO member states have provided a lot of defensive equipment to Ukraine, now it's beginning to supply an item of materiel that is predominantly used for offensive action. That is a clear message to Moscow.
That carries a risk of escalating Russian effort and spill-over into neighbouring NATO states; some NATO states will take the risk (Poland, unsurprisingly) and others, won't. IMHO, German reticence to allow Leopard 2s to go to Ukraine is a fear of escalation, the sight of German tanks rumbling down Ukrainian roads again and a need to have access to cheap energy when this is over.