Yes, I know, having all your classes/jobs on one character means you don't need alts for the same reason you do in other MMOs, but that doesn't mean that having alts is completely pointless.
Some have alts for RP reasons.
Some have alts to play with friends who are on different servers.
Some have alts just to keep it fresh and not play with the same character all the time.
Some have alts so they can play quietly without the chatter of their main's FC and friends.
Some have alts because more than one person in their home (their kids) plays the account
There's a bunch of different, completely valid reasons for having alts, and people who have alts pay extra for their subscription, but there's some things in the game that make it somewhat inconvenient for "altaholics". As such, here are some suggestions to make it a little easier on those of us who choose to not stick with a single character:
1. The ability to mail between characters.
I'm not entirely sure why this limit is in place at all, especially since you can just get around it by trading with a friend. It might slightly reduce the amount of people paying for extra retainers, but I doubt it would be that big of a deal, especially since you have to level to 20 to be able to unlock retainers and ventures anyway.
2. HUD and macros automatically copy over.
You can do this manually, but it's a pain to do, especially if you make adjustments to your HUD/macros frequently. If zone maps automatically fill out when you enter a new area on an alt, I don't see why the HUD and macros can't be carried over to all other characters as well.
3. Expand the 8 character limit, with restrictions.
This is only for people (like me) who are hardcore altaholics, but it would be nice to have an "additional service" that allows us to pay a one-time fee to add another character slot, and maybe scale the cost up with each additional slot per server so people are discouraged from filling a single server with 20+ alts for whatever reason.
4. Minions, mounts, and barding account-wide.
Some Mogstation stuff and CE rewards are mailed to every present and future character, but it would be nice if this expanded to all Mogstation purchases and any learned mounts, minions, and barding copied to other characters. Maybe Orchestrion rolls as well.
5. Estate tenant status account-wide.
This wouldn't apply to FC houses, obviously, and you would still be able to own more than one house on more than one character, but each alt would automatically be granted either co-owner or tenant status. If you're a tenant of someone else's house and not an owner, all of your alts on that server would also be tenants.
If anyone has any other suggestions (or any critique), feel free to add. :>