I know that it really does seem like an irrational answer to a problem, but lately there's been a controversy with towns that have unreasonably high taxes and are advertised to new players. After discussing this issue with three mayors and one co-mayor, they agreed that removing /t join would be for the better.
If you think about it, if new players had to be invited to a town, it would increase the need for assistants in towns. That means for somebody to join, an assistant, co-mayor, or mayor would need to be online. The assistant/mayor who invited the player would most likely give the player a plot and answer the questions the player has because the assistant/mayor is aware of the new resident.
Please critique as you wish as this is a matter that concerns me and I would like to see a resolution.