As Pasquale1234 points out, the IB is a companion. He's a "focal" character, who has his own arc and a great deal of resource dedicated to his development. Krem isn't mean to be a standalone character. He's meant to be a side-character in the IB's personal story. Krem isn't meant to be someone important, like Alexius or Gaspard. He's meant to be a character on the level of, say, Dagna or Scout Harding. Actually, his most comparable character is Varric's Bianca, and IMO he's a better character than her.
As I explained above, Krem's role - from a literary perspective - is to provide a foil to the IB. He's also a bit of an exposition machine, and that's tied with his experience with the Chargers (to give them a face, when we get to the personal quest choice for the IB) and to provide background on why he's an exile and outcast too.
I think, however, it's completely misreading and misappreciating Krem to say: "Krem doesn't have an unbending personal ambition of Solas where his desire is to restore the Elven people to their former glory and retain his godhood, even if it means giving an orb of power to a megalomaniac such as Corypheus." Krem - to be only person who he can be - chose to risk Tevinter prison to express his identity. This willingness to stand up to authority is the direct contrast to the IB, who - when he has doubts - surrenders himself for re-education. Krem is meant to be the brave contrast to the IB's - at least in his early part of his narrative arc - cowardice.
Let me put it differently: Krem is meant to provide us with a different perspective on the IB, in the same way that the IB - from a lore perspective - is meant to provide us with a different perspective on the Qun. The Qun is all about identity: who you are is what you are, everything that defines your worth without allowing you to choose that for yourself. Krem is someone who -in virtue of his gender identity - is someone who has been defined his entire life on who other people believe him to be without being allowed to choose that for himself. Identity - whether it's gender identity or something else entirely - is at the core of the IB's story and the IB is part of that arc.
I can't argue with you that you didn't find Krem interesting. Like I said, interesting is subjective. Though to me it sounds like you primarily find supernatural characters (you list Flemeth and Cole) interesting. My post was really confrontational, and for that I apologize. But I think Krem is a first rate character concept that - ultimately - isn't well executed in practice by PW. But he's a "first rate" character concept because of how closely he ties in thematically with the IB's personal story. Look at the final quest:
When the IB sacrifices the chargers, he's broken. He's never fit in with the Qun, he's always chaffed under it (see how
every time he talks about the Qun coming, unlike Sten from DA:O, he looks at it like a horrible disaster, that will wash away and crush this society in Southern Thedas he's come to love). That's the opposite of the choice that Krem makes, and to make that choice he has to sacrifice Krem.
The problem with the execution is that Krem ends up basically being the IB's
morality pet (to use the TV tropes term) and is a bit of an exposition machine, but to look at Krem as somehow being there to fill a quota misses the richness not just of
his character, but the IB's own character.