SE is slowly eliminating the reasons for players to need alts.

We can already have every job on a single character if we want. No reason to make a new alt just for the sake of playing a new job.

New Game+ might eliminate the need to make an alt to replay through the MSQ and side stories (which is the primary reason why I make alts). We still don't know enough about NG+ to know if it will effectively serve that purpose.

World visit now allows us to play with our friends on other worlds in the same data center so we don't necessarily need to make an alt in those cases. We still need alts to play with friends if they're spread across multiple data centers, though. I imagine that might always be a problem across regions even if they're eventually able to connect all data centers within the same region. But if we're making an alt solely to play with friends, there's no need for that alt to have everything. Just level it up and and focus on getting the items that alt would actually be using instead of going to into completionist mode trying to do and get everything on each character.

Like others, about the only alt "enhancement" I would like to see is more of the mog station items being made account wide instead of single character. Jump and skip potions already exist for those players who want to get an alt up to speed to play through content with friends.