Ideally, more so than any one key feature that works great as an advertising point but inevitably falls through as half-assed as per those prior, I'd like to see several sensible general improvements:
  • Item bloat consolidation and retainer reforms;
  • Leveling cohesion improvements;
  • Character customization improvements, especially with regard to choice of emote, voice, and animation sets, including on-the-fly 'mood' sets with deeper cutscene interactions;
  • Adjustments to alt interactions, including optional account-wide benefits such as to one's Armory Bonus and optional story interactions with one's main by way of reference and potential quest-skipping;
  • "Living world" adjustments, with due effects on FATEs, market standardization and flow, and crafting opportunities;
  • Adjustments to Squadrons, Chocobo training, and Trusts, especially across earlier levels, to allow for greater quality and cohesion in and between each;
  • ARR and HW zone improvements, complete with pre-patch rewards as reasons to use New Game+ or create alts to view said improvements;
  • Central zone mechanics in new zones by which to offer a bit more specific gameplay to zones and sections therein, such as migrating herds, key monsters, environmental dangers, unique modes of transport, or the like;
  • Improvements to in-game learning features, such as the addition of a far more useful parser than is provided by ACT, in-game guides, and a revised Actions & Traits pane that can now act as a manual, organizer, and simulator for combat considerations, rotations, and the like;
  • An Enmity system rehaul;
  • Greater active mitigation across tank kits;
  • Improved button-efficiency across all kits;
  • Retuning of mob damage and damage procedures as to allow for more eventful, healing (neither spammy nor based solely in minimalization atop greatest per-GCD output);
  • Greater means by which to have meaningful (teamwork) capacity outside one's own role within job kits, predominantly through undermechanics rather than specific kit actions;
  • Jobs reforms such that each in a given role provides equal capacity on the whole, nearly equal capacity through the majority of its parts, but via very different methods as to remain distinct from each other, with Role Actions removed in favor of job-unique means.

Etc., etc.