Populate other cities
I think Lion’s Arch sees a lot of traffic because people use it as a place to hang out while they wait for their group to organize. The other cities are a little harder to use for that function, not only because their services are a little less conveniently placed (although I’d definitely agree on that point), but also because they’re less centralized.
Especially at lower levels, where people don’t have the full world explored yet, it can be pretty inconvenient having to travel the world to meet up with friends. It makes sense that if my Sylvari is meeting my friend’s Charr that instead of meeting up in the Grove or Black Citadel, that we’d both go halfway and meet in Lion’s Arch.
Rata Sum has a pretty sweet merchant quarter, although it doesn’t have the Mystic Forge.
I don’t know what would be a good fix, but it is a pity the racial capitals don’t have more reason to visit them, other than for pure sight-seeing. Divinity’s Reach is hands-down my favorite place in the game, so I was really happy when Beacons of Kryta and the Crown Pavilion gave me more reasons to spend time in it. Hopefully the other cities will get some Living Story love sooner or later.