Regarding Abyssea, when it comes to getting seals people want you to be a certain class even if the monster that you're facing doesn't drop the seals for that class.

Why should I have to level up a whole other class just to get accepted into a party to get seals for the class I actually play/care about?

And to be honest, "Proc-ing" something isn't really fun anyway. As for a challenge, it's not even that either. I don't see the point in it really.