User Game Element Development?
Reasons why not:
The staff have better things to do with their time than sift through submissions. For example – creating their own armour sets to go in game, fixing issues, etc.
You can’t ensure quality in things people submit. Even if they are reviewed by staff the chance of users actually putting everything in all the right places, coding, modelling correctly etc is slim to none. It’s not feasible.
However:
I would love to see the return of the design a weapon contests that were held occasionally in GW1. Some of the games best looking weapons were created based on winning submissions by users. It’s always cool to see what people come up with.
I’m so happy to be able to use the Wayward Wand in GW2 simply because I know that it was designed by a user for GW1 which makes it just that bit more special and cool.