(edited by Will.9785)
Less items in collection = more legendaries
So the dev team gave up on the legendaries because the collection were too much work.
I have an easy solution for you.
Stop including so many items in the collections.
For example, does there seriously need to be 30+ items in the tier 3 collection? Its not like the extra items contribute significantly to the length of the quest. Most folks will still bang it out in a day regardless.
If the dev team would have cut the number in half they would have gotten twice as far.
Matter of fact, you could drop items from existing collections and shift them to other (new) ones to save even more time. I know some of the items have ‘lore’ behind them but its not like it would take much to change an icon and text but keep the method of acquisition the same.
I think its more the art thats the problem they need said artist to do black lion weapon skins/gliders etc instead.
MB said that all but the art took 1 month for each precursor.
https://www.guildwars2.com/en/news/hot-new-legendary-weapons/
From brainstorming to testing and bug fixing, building everything for a new legendary weapon reasonably takes about a month, not including the art for the weapon. That’s about a week per themed collection and a week for the economics, recipes and other random tasks