FATEs are just one thing. Variety is good.
I like that hamlet defense thing the OP described; I have to wonder why they scrapped it going into 2.0.
I can give you an MMO that does open world content in a much more varied way: Rift. You've got, of course, rifts, which come in a variety of types - minor, major, crafting, pvp, hunt, raid - and zone invasions, which have a variety of different objectives, including ones that are more pvp-oriented. Instant adventures are like rapid-fire, neverending group objectives that can take you all over a zone; you can queue for them or just encounter one out in the open world and join it using the game's public grouping feature. Artifact hunting is another biggy, especially with the new profession out, but people still also love completing collections; if you use Quantum/Omen sight (a special ability you can unlock by purchasing it with planarite once you hit 50), you can see special artifacts, as well as the entrances for the game's 10 man content, Slivers. The whole open world is littered with puzzles tucked away in mountains, or atop buildings, or in valleys, or whathaveyou, many of which give achievements or other rewards upon solving. Then there are those standard things such as rare mobs and material gathering. There are plenty of dailies and weeklies as well, if that's you're cup of tea.
FFXIV has... gathering, FATEs, dailies and... what? This game just needs more.