S Ranks Need to be Increased in Difficulty. Period
I don't care about the people who go afk all over Eorzea, nor others from different servers trying to cross over to participate in another server's hunts. If you make it, great, and if not then too bad.
However, what I have a problem with is that people are literally creating cross-world linkshells for the sole purpose of forming a snipe team to travel to other servers and snipe their S Ranks! These cross-world linkshells are being promoted in party finder too. This is extremely unfair to the other spawners who put in the time to spawn S Ranks for their server community. With this cross-world play feature being implemented in patch 4.5, it's an open door for snipers to come into your world and take a hunt from you before you (or anyone else on your server) can partake in it ... let alone reach the hunt in time to get even one hit in.
I am not a fan of these snipers just as much as the next hunter is, and Square needs to implement some way of increasing the difficulty of A Rank and S Rank hunts. Whether it be increasing their level to that of the level cap of the expansion (currently level 70, soon to be level 80 with 5.0), or turning hunts into Notorious Monsters similar to that of Eureka where you need hundreds of people to help take down an enemy. If neither is an option, then either ban cross-world hunting from cross-world play or just don't implement the cross-server play altogether.
Personal preference: I like the servers being isolated as they are without the cross-world play. If I really wanted to play the game with my friends from other servers then I would just do a world transfer to that server instead.