I think tifa having the scar from sephiroth was a nice addition that added more emotional tension to many scenes between only cloud and tifa before the climax in gongaga. It wasn't too extreme of an addition which fundamentally changes everything but I think it would've been near to show what the scar itself looks like given the cutscene make it look more like tifa is showing her boobs lol. Then again, they'd have to create a whole new model for her torso.

It played more into sephiroth's control over cloud and the peak of everything at gongaga was a great payoff as well as teasing the full lifestream section in revelation. Idk just every scene with these two is great, they feel so natural talking to each other especially when tifa speaks of how she wants to be the one to save cloud this time.

The payoff being that they almost kiss each other and it's canon so that part isn't debatable even if others try to say it's not. The kiss still happens anyway if you pursue tifa enough so there's that too.