Tazel carried it pretty well, too. I never thought she looked particularly small, although Timothy Olyphant, the star she often had to face off against, is only about average height himself. But I never thought Tazel looked silly or underage, even though her character was a deputy marshall, whose jobs mainly involve being bodyguards and dealing with convicts & fugitives. If there is a law enforcement agency where size should be a thing, it would probably be the Marshalls' Service.

I think Tazel could probably do a good job as Moiraine, but then making the Cairhienin black would be too weird. Elayne has very dark-skinned ancestors (Ishara was as dark-skinned as one of the Sea Folk [and she's Rand's ancestor too] ), but her father?

On the other hand, Emilia Clarke would be horrible as Moiraine. She's crap at acting regal, she looks childish and her build only makes that look worse. In "Solo," when she wore formal attire, she looked like a little girl playing dress-up (and the scene in Lando's closet didn't help). Imagine instead of one of the times she stared into the middle distance and uttered some nonsense about "breaking the wheel", she was deflecting the quite reasonable questions the protagonists often posed with "the wheel weaves as the wheel wills". NO.

Pike would nail every aspect of Moiraine's role far better than Clarke. And even though she's slightly too young as opposed to much too young (although Clarke IS in her 30s, she doesn't look it, much less look the part of an authority figure in middle age. She definitely does not look like she could get away with calling a 24 year old "child" ), she could pass for someone slightly older.

I think overall, the presense and demeanor are going to be more important than the height. It might be weird, since they are very unlikely to cast someone as tall as Rand or Lan is, but it's one thing to read about Moiraine dominating them despite being well over a foot shorter and something else entirely to convey in a photographic image. It was really really plausible that charisma vacuum Kit Harrington posed a threat to Emilia Clarke's authority without having to do anything in opposition to her, that people would be more inclined to see him as a leader and ignore her superior qualifications. There aren't many male actors I could see that being said about with regard to Pike.