@otakufan:
Let's be fair here - the Strawhats were never really shown to have a "helmsman problem" either. Luffy failing at something ship related is practically a part of his character thesis, but in spite of that, the Strawhats as a whole functioned just fine without a dedicated helmsman for real-world decades. While Jinbe's role as helmsman might have been foreshadowed and predicted, his proficiency at that role was by no means apparent until the "Green Room" stunt during the escape from Totland, well after his joining the crew was a certainty.
The Strawhats may never really have been shown with a "lookout problem", but we also haven't really been shown what having an particularly effective lookout in place could do for the crew. Usopp acting as lookout can't simultaneously man the cannons. Chopper acting as lookout can't treat injuries. Nami acting as lookout will have a harder time keeping an eye on the currents and weather. And so on. Just because other characters CAN do the job doesn't mean they're MOST EFFECTIVE doing the job.
I'm not saying "Carrot4Nakama" is guaranteed, by any means - she needs some focus and to take the opportunity to show her stuff, both as an individual combatant and as part of the team. I just feel that the "Lookout's not a real job" argument is unnecessarily dismissive at best, and the "Even if it were, Usopp can do it better" arguments are improperly lumping it in with his actual role as a marksman. While similar at first glance, the two roles don't always sync up perfectly, and I think a highly mobile character serving as a dedicated lookout/spotter could synergize well with the Strawhats in general, Usopp in particular, and solve what has been mentioned (even if only in an SBS) as something of an ongoing health issue for the crew.
Just because you don't see the need doesn't mean the need isn't there.
Again, the problem boils down to "show don't tell".
We can spend hours theorizing circumstances where Usopp is manning cannons, but needs a dedicated lookout to help him out. The problem is, if Oda doesn't show that problem happening, then it is not a problem at all. That's how he does things.
(Never mind that Usopp awakening CoO makes the need for a Lookout even less needed. She needed Viola to tell him where Luffy and Law where, but then was able to just see his auras).
Every single Straw Hat has been accompanied by feats that showcase their expertise and why they're important. We saw this immediately when the Straw Hats were sailing to Whole Cake. The moment Sanji leaves, food becomes a problem. Helmsmanship also suddenly becomes a problem, foreshadowing Jinbe's necessity to be with the crew. It wasn't a problem at first until it was, and it had to be showcased. Oda has already stated he never leaves story-important details in the SBS alone.
And right now, we had the perfect opportunity to show why a Lookout might have been needed, during a naval battle and an infiltration in enemy territory. And in both cases, Usopp was used and performed both roles with no problem at all. Compare this with Jinbe, who immediately took hold of the ship's helm after his return and had Luffy telling him orders to chase after Kid. That's how Oda does things. He puts the crewmates in thier designated spots when the necessity comes.
And now that we are in dry land, Carrot's opportunities to show why she would be the crew's Lookout are very little, especially when she's away from where most of the action is taking and fighting an enemy that's almost completely detached from the main conflict.
–- Update From New Post Merge ---
@BobLoblaw:
People seem to be forgetting that before that one chapter in WCI, the SHs never needed a helmsman. All it takes is one chapter to change anything. Like I've said, Oda makes things important when the plot requires it.
SH Crew: "Hey Usopp. Can you spot any dangers on this island with your amazing vision?"
Usopp: "Umm…"
Carrot: "Don't worry. I got this."
https://i.imgur.com/X77Izcn.png
https://i.imgur.com/SqH6bOa.png
Too bad she couldn't do that in the very definitive final battle of the Saga, where we could see her working with the other Straw Hats and putting those skills for use, like how Jinbe did.
But nah. We already have Usopp.