I'm 50 50 on this.
Custom titles would be cool but giving a player the option to fully customise their title could result players picking racist, homophobic and 18+ words in their titles, Some could even be in a language us or the Staff members aren't aware of and that's not okay and if players are using inappropriate words as their /Nick I would advise you to report them on forums.
Instead of giving players the opportunity to create custom titles, Players could suggest words for the next title pack. Every month 12 new titles are released and the previous 12 becomes rare a collectable perk
What we have now is simple and it's great. It's an easy system and it doesn't give staff members another reason to worry about