Tinkers offer a lot of services currently that are exclusive to the UD. While many of them seem to be designed to compensate for a smaller player base, there are also some things in there that are UD exclusive 'cookies' that no surface merchants seem to offer - such as:
- Enchantable bracers
Keyrings
Headbags
The other functions, such as language learning and repairs, would also be wonderful as a means of motivating an exploring/adventurous attitude; people will want to see what these merchants can offer them, and will more than likely start travelling a bit more to find them and check back in with them over time.
Suggestion: Make a tinker-equivalent for the surface server settlements and/or the Cordor area (since it's marketed as a big trade port).