First of all, I don't want this thread to be the same old debate about 1.X, talking about things that aren't compatible with the current version such as the graphics, seamless zones and so on, but rather, the smaller details - lore and world-building and so on that were enjoyable and could be brought back without too much hassle.
For example:
- Having dreams when sleeping at the inn, and finding items when you examine the bed.
- Merchant NPCs having small talk instead of just a buy menu - I recognise that for convenience's sake you want to have the menu open straight up... but some of them already have sub-menus, and it might be fun to see what they have to say.
- NPC linkpearls - it's now easy to travel the whole world to speak to people and there isn't a need for them to give you advice, but wouldn't it be fun sometimes to see what your favourite NPC had to say about something? I think this might be a lot of effort, but we know people have already requested a dating sim...
Characters and concepts from pre-2.0 have continued to return all the way up to the present - just look at the design of the Crystarium originating in a 2005 tech demo... so is there anything else would you like to see make a return?