It’d be interesting if it was revealed they made titanforged by using elemental spirits and binding them to the forged beings they create … It’d give more detail into explaining:
- How they have souls
- Why some are more elemental-aligned or comfortable & friendly with elementals, despite their directives and history
- Vise-versa of why some elementals are comfortable, have friendly bonds or sometimes are even open towards having outright loyalties or partnerships with Titanforged
- and even the development of some of their personalities later on.
That being said, it’d be curiously interesting to have revealed some titanforged were forged from the spirits of elemental princes / princesses or some form of other higher class elementals …
Also to note:
That some elementals hold a deep grudge against the titanforged — Apart from locking them away in the elemental planes, them once being their own kin would give some furthermore additional precedent to some of their ill-harbored feelings that are rooted deep to their personalities, whether they remember or not, as there would be a sense of either betrayal or an uneasy sense that they were twisted into something aberrant to themselves.
Alas, as we have also seen with the Earthen and their memories being removed or altered, it wouldn’t be too far fetched to say with some higher-class elemental spirits — That their memories of their elemental life was forcefully abolished in place of their new directives and presented the ultimate conspiracy of being forged solely by the titans for a ‘Noble’ purpose.
- The above would give some further context too, towards Iridikron’s uneasy views upon the titans as well.
Given we found out with the Dark Iron Dwarves questline – That Ragnaros can still surprisingly be resurrected (which implies that the emperor of the winds, Al’akir – could also be revived too) – There’s the grand possibility of an added notion towards the titans, that they may just had perhaps weaved even MORE conspiracy than most had already surprisingly considered 
…
Anyway! 
— Feel free to speculate further, discuss and brainstorm various possibilities upon the above, that would revolutionise the elemental world & lore amongst Azeroth! 