I bolded an interesting part. To us readers zoros sacrifice at TB already showed us that he is ready to do anything for luffy. Why repeat that again while trying to become stronger? The man is ready to sacrifice his life therefore his dream for his captain. There was no need to repeat that by introducing Mihawk and thus forcing the character zoro to learn from the guy he wants to beat one day…
Could mean foreshadowing for Zoro injuring\dieing to help somehow Luffy and so not achieving his own dream(even when i think Oda would not go THAT far).
For me it seems like Oda wants to show us that now after a big part of the journey Zoros goal of becoming the greatest swordman has now changed.
s not anymore his biggest goal. Zoro wants to be now the best swordfighter, because it would be necessary\important for Luffy gaining his goal! Its now more like Usopp wants to be a brave warrior,because it`s necessary to help Luffy.
So it is also with the rest of the crew..all their dreams they try to reach are helping Luffy in someway or another, thats why they all are still aiming for it.
Recently Zoro was always portayed as the one who stands behind the crew (Usopp-incident in Water7 he was the one who made clear that Luffy don`t have to back down, Kuma-incident already mentioned) and i guess Oda wants to make it 100%-karat clear that Zoro is not any longer the lone wolf with only that one fix goal in his mind.
Zoro is the vice-captn who sacrifices everything for Luffy and stands behind the crew with everything he has.
(and I think that he knows that he could fulfill his promise to Kuina the best way like that–like Zoro said:The PK and the best swordfighter seems to be a ideal team)