This has been something that's always bothered me, while its skill level is not lackluster, it does seem lacking for a job that in recent updates has been urged towards the side of using Ranged Attacks as a way of dealing damage. This can clearly be seen in the Magian trials, or the new job ability Triple Shot, corsairs have been excluded from both the dagger and sword trials - the usual weapons of choice for corsairs to build TP, instead we're pigeon hold into doing Marksmanship trials.
I wouldn't have a problem with this if it wasn't for the fact that our Dagger skill has a higher cap than our Marksmanship, and even still our Parry is the highest in the game. It's as though they had to choose something to give Corsair an "A" rating, possibly not wanting to encroach on Rangers.
I'd love to see Marksmanship raised much in the way that Hand to Hand skills were raised for the Puppetmaster job, I don't really see the harm in it, nor anything that would throw off any game balance from doing so. Rangers still have access to the strongest bullets available, so why not at least give us a few more points of skill to compensate, I mean, we're pirates not fencers.