As a story idea, I think amnesia can be an interesting plot point. But FF games, and media in general, idk I feel like it's used more often than it should be. As Howl kinda said, there's a lot of ways to tell a good story and oftentimes when amnesia is used in one, it feels kinda lazy. Like they have a plot idea and they're trying to figure out how to make this and that work and just go "Eh screw it, the main character has amnesia! Done!"
I think having a friend who knows but keeps quiet is a bit more interesting. Has more conflict in their personality; why are they hiding the info? Is it selfish or selfless, because they have ulterior motives, or because they have a very positive way for doing so, etc?
Still don't get why Tifa kept quiet about Cloud, except that maybe she was really worried at his mental state already and didn't want to drive him over the edge
I've only played VI once but I feel like Terra's case worked well? Like it didn't feel cheap.
I also liked Fang and Alyssa's 'versions' of it. I feel like there was a good reason for their amnesia and it didn't feel like the writer's just slapped it on because cba. Imo anyways
Going forward, I'd like for FFXVI (whenever that happens) to try and not have a character with amnesia
or orphaned protagonists. Use their collective brain muscles to come up with something more unique and less used.

I'm not against seeing either again in the future of FF games, but just give it a break for a bit. XD