Problem with naval battles is what would you use for attacks? cannons? I guess you could use Sunny's gaon cannon but then it'd be just as easy for at least a few of them to just break ships like they were planks (like when Ace sinks multiple billions ships with a single punch). You could think about ramming ships, but then why would you not just jump over and do some damage without having to damage your ship in the process. To me, the most exciting part of naval battles is the planned maneuvering it takes to avoid the other guy's fire and then return your fire. I think this would be incredibly difficult to portray this without making it really boring for most people who don't necessarily understand or enjoy the process.
And seriously, as much as Usopp was pegged to be the cannoneer when they first got Merry, they're so fucking useless. Cannon fire from Marine Battleships were portrayed as nothing more than a minor annoyance that could be swatted away with kicks, punches and sword slashes.
Whilst that's all true it still doesn't take away the fact that its a pirates manga and we haven't had too many naval (maybe enies lobby and ed war) and the ones we have seen are either one sided or not fully shown so something on the lines of luffy-law alliance(including all the people luffy allies with in nw) vs kid apoo hawkins alliance(including their allies) would be AMAZING. Plus these guys are bound to have somethings in their ships to make up for the weakness of cannons. The sheer number of ships would actually nullify that weakness cause even gol d roger struggled against numbers if you recall. So not exactly a battle but more like a war is something i really ​want to see