You can't compare WoW and UO. They are two very different games. The issue of abandoned cities in WoW stems from the fact that the towns act as adventure hubs for the current expansion. So historically speaking, in Ciassic WoW, on the Alliance Side the most packed cities were Ironforge [Because it was closest physically to Molten Core and Blackwing Lair] and Stormwind, because it was the Alliance capital with all important services based in the town, and SW is just a short flight away from Ironforge or a subway ride. For Horde once again, it was Orgrimmar because Org is so well centered in the world everything is near it. But even back then in the classic game Darnassus, Thunder Bluff and Undercity were not used because of how out of the way they were.
Then came Burning Crusade they added new racial towns for the Dranei and Blood Elves [ Exodar and Silvermoon City] which never gained popularity because once again, centered way out of the way and the adventure base for that expansion was Outland and so Shattrath City was where everyone went, abandoning the now outdated content and old cities. Next expansion, Wrath of the Lich King - Adventure shifted to Northrend, new main base became Dalaran. Then Cataclysm came and they decided not to add any new continents and instead expand on the existing world, so everyone went back to Stormwind and Orgrimmar, also, these cities had portals to the new areas built in and all sorts of special NPCs and services were added *only* to these towns that could not be found outside so even though everyone was back in the old world, there was no reason to visit any of the old world towns anyway. And now in Pandaria it's the shrines and in a few months when Warlords comes out everyone will abandon the shrines and move on.
In UO's case, UO has never been a game with content that leads people around. Even in classic UO, Britannia had way too many towns to begin with. Back in the day on Atlantic [2000] I remember a packed Britain, people would also banksit in Trinsic and Moonglow. And really, that was about it, the other towns were always empty. I think bank sitting had to do with convenience. Britain has all types of shops within walking distance of the bank. Trinsic has most shops and Moonglow is just small and compact. Then came Luna with all shops within steps of eachother and housing outside the gates creating the perfect one stop shop. Zento tried to copy Luna but ended up being a failure because in spacing everything out so far it still could not compete with Luna which is more of a shopping mall than a town. Putting unique quests or services won't work because people will just grab their reward item and recall out to Luna again.
And then we have the issue with UO's population. It's very low. Even on Atlantic there are places I can go and not encounter another person for hours. On smaller dead shards its even worse. Shards like Sonoma don't even have bank sitters! Luna is as much a ghost town as all the other towns.
Some ideas I can think of, at least for crafting would be to do like the public soul forge in Royal City and give a success bonus to crafting when using public forges. Maybe melee skill training can get a boost in public fighting pits in Jhelom, Mages could train magic skills faster at the Lyceaum, Bards can train music skills faster at the music conservatory in Britain, Paladins can gain faster in Trinsic or Luna, Necromancers can gain faster in the Necromantic school in Umbra, etc.
At least this way there would be a REASON to go to town, for a bonus you cannot get outside.