Whatever the suggested improvement can be is problematic. Non-mechanical rewards amount to an achievment system, such are necessarily limited in number and can thus be completed entirely leading merely to a new boundary (unless we make open-ended ones, like your troll kill count

), it's harmless but won't solve the issue of continued development.
If it's a mechanical reward it will have a bound or will either be useless or overpowered, if it has a bound you merely pushed a boundary and people will eventually get there, if it's useless no one will care and if it's overpowered ... no need to develop that point
