I do get that Legacy Items are nothing new for the ARPG-Genre and they do have their place. They are a nice nod to the development of a product and having them may be quirky.
The single thing you should always avoid though is having your Legacy Item remain as Best-In-Slot (BIS) gear. This will create a scenario where you have a few players that "have" and a ton of players that will never do. And we are talking about the thing everyone wants as it is the best thing available.
I am arguing this from the side of someone that also has Legacy items at ILevel 40 that simply are SO MUCH MORE better than anything I could get for a drop or reroll so far. And I am well beyond 90.
Instead of splitting the playerbase into those that just happen to have god-like items, we should try to level the playing field.