Titles are suppose to represent an achievement you accomplished so being able to write your own "Title" would defeat the purpose of it. When people look at your title they're suppose to go "Oh he did the exploration achievement or oh he got one of the luminary craft weapons". Titles shouldn't be something you're forced to obtain because of the stats they offer but rather something you want to obtain to because it's a goal of your's. When you add stats to titles then people are forced to obtain so they don't gimp themselves rather then getting it for their own objective.

Though what would be neat is if your could have a front and back title, since the placement of the title is based on how it's worded it would be nice to show off two titles if possible rather then only being able to choose one lol.