Questing

Talking about open world questing (sidequests, main senerio quests, ... )
I'm usually not the type of person who likes to compare games when there are obvious pro and cons to most MMO which makes it hard to compare. But questing is the only thing that really stands out in FFXIV in my opinion. The stories are interesting but the objectives are very linear and boring. Compare this to other MMO's, like WoW for example and you'll be amazed by how much more variety there is in quest objectives and you'll notice how much more interesting it makes them.

FFXIV does still nail the storywriting in both side and main quests but they have to make the objectives more interesting to keep the MMO community (final fantasy fans likely don't care) interested in the game. It always comes down to kill this, gather that, talk to this person. It's always linear, they don't dare to give you some freedom.

I wonder if this might be due to engine or open world scripts limitations, although it's probably just because it isn't their focus.