I’d say it’s still an oversimplification to say that the Matoran straight-up couldn’t love until witnessing romance between Agori, and an illogical one at that: After all, aromantic people don’t magically develop romantic emotions just because he or she sees a couple together. In order for Greg’s idea of “learning to love” to work, the Matoran would have to have the potential for such emotions in the first place.
The only interpretation of Greg’s words makes sense, imo, is that the Matoran (or at least, some) developed the potential for romantic feelings as an unintended result of the Awakening, but just didn’t understand or recognize them as anything beyond really close friendship - which would be consistent with the fact that, even in the case of Hewkii and Macku, they never actually refer to “love” or “romance” by name (except Matau’s brief “romantic ride-drive” moment, but we can chalk that up to creative liberties on the film’s part).
Furthermore, going by this interpretation it would still technically be true that Matoran “could not love”, since romance as a concept did not exist in Matoran society. However, after discovering the concept through the Agori, they could be able to better understand the associated emotions. Plus, this would not necessarily invalidate relationships that have been established - those bonds could still exist, just without the characters recognizing them as romance.
Personally, I prefer the potential for love (and established romantic relationships) to have always been there, but I think they’re better left off to the side of the story, and it was good that they were never actually explored as anything more than a side thing.
Just because love has the potential to exist, that doesn’t mean it automatically becomes a focal point of the story. After all, when we got relationships between characters, it was always very much a side thing, and never affected the story.
Edited for triple-post. --John Smith