A lot of people love Lego Ninjago sets and so am I. I think that "Legacy" was a very successful theme of sets and it must be brought back. Legacy sets were a way for us to get our hands on old sets that have an updated design and it was an excellent idea!

We had a few waves of these sets and they were very good. Everyone loved them so why not bring them back? 

Ninjago Legacy was replaced by Ninjago Evo and here's why it's so sad:

1. These sets are (or at least were before ndr) considered non canon, because of characters that were never seen in the Ninjago series. What's wrong with that? Most of the time, people buy sets because of the TV show, when you see a cool character in the show - you want to get your hands on him; when you see a cool build - you want to get your hands on it. That's the point of Ninjago sets - they give you a part of the show.
2. Evo sets are sold very badly. When I enter any toy store and look for Ninjago, I always see lots and lots of evo sets. No one buys them. What about Legacy? Everyone loved them!

So what is so nice about bringing back Legacy sets? We can get updated retired sets from seasons 5-15; it's an opportunity to create more new sets for older seasons and integrate some new characters in them; It's something that Ninjago fans loved and want back.