QoL feature for better remembering players that went by a different name.

[Nezerius]

If they want you to know their old name, they'll tell you what it was themself.

There are lots of reasons someone might change their name, and many of these reasons include some desire for anonymity.

Going to assume the #1 reason of the ones you're referring to is stalking, a simple namechange isn't really going to avoid that. Anyone who gets to the point of stalking will likely rely on a player's lodestone id, which always remains the same.
I don't think this reason is enough to not implement a feature that the OP is asking for, especially since they could just make it a feature that players could opt out of if they wish to.

A feature to remove our name from other people's friendlist is something that is often brought to the table by many players.

Yoshi-P mentioned about a friendlist overhaul, that'll include this exact feature, during a Korean live letter back in January. Although I don't think anything's been mentioned about it ever since.