I hate to say this but even with auto-kick for AFKers Limsa would still be busy and prone to issues and overcrowd. And you wanna know why? It's the only city worth going to if you're server hopping to buy stuff on the MB or checking prices. That's it.

Yes, people on your server might prefer going to Limsa for various reason, everyone else that isn't on your server will also go to Limsa but for the reason I listed above. For as long as you have a Market Board right next to the same Aetheryte used to Server Visit, Limsa will remain the busiest place in the game due to convenience. There will always be 200+ people on that map, the only difference an AFK kick will do is replace all the FC tags with <<Wanderer>>.