Boa pergunta. De acordo com este relatório da Boskone em fevereiro de 2013 , há um razão, mas GRRM não irá revelá-lo, pelo menos por enquanto:
I asked whether he would comment on his choice to call these chapters “Ser Barristan” instead of continuing with the titles from ADWD, and he replied that he has “a method to his madness” for promoting characters with descriptors to named characters but that he didn’t want to say more.
Por que vale a pena aqui é uma lista de todos os títulos dos capítulos sem nomes:
The Prophet, The Captain Of Guards, The Kraken's Daughter, The Soiled Knight, The Iron Captain, The Drowned Man, The Queenmaker, Alayne I, The Reaver, Cat Of The Canals, The Princess In The Tower, Alayne II, The Merchant's Man, Reek I, Reek II, The Lost Lord, The Windblown, The Wayward Bride, Reek III, The Prince of Winterfell, The Watcher, The Turncloak, The King's Prize, The Blind Girl, A Ghost in Winterfell, The Queensguard, The Iron Suitor, The Discarded Knight, The Spurned Suitor, The Griffin Reborn, The Sacrifice, The Ugly Little Girl, The Kingbreaker, The Dragontamer, The Queen's Hand
Quanto ao motivo do raciocínio do GRRM:
Some have speculated that perhaps the players in the game of thrones are given named titles, whereas "pieces" in the game (IE, minor characters) are given descriptive titles.