My thoughts are more likely bias, as i hate runescape and have not played in a long time.
But fuck that skill and everything it stands for.
Theres 3 ways according to the post to train this skill
Ship building (May as well be construction/crafting)
Navigation
+ These 2 things basically being the same thing are a basic fundamental of any RPG. Traveling.
Exploration
If i wanted to have to sit and shift myself to charter boats (Which are already in the game, go to any port and you will be able to charter) to unexplored areas, they may as well have introduced it as a skill when they released 'Ports' some time ago in RS3. But they didn't want to introduce it as sailing, only to further joke the community that is the players, into thinking so. Instead they release it as a minigame that you have to grind out. More than any other minigame if you actually want to be a top competitor in PvM. More than the majority of skills themselves. I wouldn't be wrong to say also that it would take longer to grind out that minigame for it's rewards, than to get any skill at all in RS3 to get to 99, Some skills to 120 infact.
And by the sounds of the PvP section of the blog, the new world will not be in your own instance but very public, so all islands are open to public free navigation to find the quickest route to your destination without even knowing a single thing about the skill by simply looking up any guide, leaving any sense of accomplishment dead.
TL;DR
So instead of having the casual Charter for transportation or quest to unlock new areas, you have this super uncreative skill, generated against the will of the players (according to polls and previous statements of never releasing this skill) that will probably result in micro managing schedule based training for most players. and imo will probably end up being on, once again, the worse side of updates.