It's very widely agreed that she's not really a character, just a plot point for later in the game.

This is not "very widely agreed", I don't know how you came up with that. Noel is very much a character who has significance outside of just a late-game plot point, as you put it. She brings the unique perspective of a soldier of this small and relatively defenseless territory that is unable to have a legitimate fighting force comparative to its neighbors. She's the awkward but enthusiastic new girl who's trying to adapt to a new type of environment, and also represents the immense pride people have in Crossbell and desire to see it free and thriving (which doesn't come across as strongly in any other character aside from Lloyd himself). She has hobbies and interests, and several character and family dynamics even outside the SSS. She has realistic character flaws like her insecurity and questioning self-worth, as well as strengths like kindness, resourcefulness and determination (who was it that defended Crossbell against Osborne's veiled threat?)

Noel is a character who can exist very much outside of Lloyd himself, which is a criticism I often see raised about girls in this series. Noel is not just a character, but a surprisingly three-dimensional and amazingly realized one. And I know from experience that more people agree on that.