I have 3 active alts in FFXIV, where in WoW I had around 14/15. I'd like the game to be more alt-friendly because I'd much rather continue playing FFXIV than switch to another game when I get bored with my main. I make them for fun, to redo the MSQ and also because I find levelling everything on one character too hard because of limits on armoury and inventory space.

What I'd like to see:
-Sharing houses with alts enabled - This wont solve the housing shortage but it will help to ease demand.
-Being able to mail your alts

It would also be nice if some achievements, titles and mounts were made account wide (not rep or job-specific mounts) but that's a minor issue compared to the 2 above.