I'm not so much defending the current relic quest line as stating why it is. I'm also realistic in the resources available to produce it and am happy to have it even as it is rather than not have it at all because they didn't have enough spare resource toproduce unique content for it.
By the same page I will point out again that there are things like puzzles that many players are very much against. Even the very simple puzzles of the Broom quests were too much for some people.
I do however think more variety in ways to progress the quest would be a good thing. However this wouldn't lower the amount of grind, simply what you chose to grind because the grind is part of the justification for the reward in the first place.
I would make two points about the relics.
First, I don't like the RNG aspects even though they allow the option at least for levelling alternate Jobs. I would far prefer a system like lights where you 'charged' the luminous crystals with a chance on every FATE for a bonus spike of charge with perhaps the special FATEs having an increased chance of a bonus. RNG is rarely a good mechanic in any grinding scenario unless its well mitigated by alternate progression options.
Secondly, I think one way the new anima chain is very much superior to the old chain is the amount of options of what content we can gain progression from doing. This makes the grind far less cumbersome since we can gain progress from stuff we were doing anyway. I would also think opening it up further to include things like EX tokens and such would be a good thing, as long as people understood it wouldn't make it any faster. The weapon is going to be a grind. You want a weapon of that level by doing hard content you should be doing the hard content that rewards a weapon of a similar level.
Im very much keen to see them experiment with quests and puzzles and such. I don't however think the relic/anima questline it the place for it. Too many people who will be attracted to the anima weapons won't want to see content like that or find it fun.