I have to agree here. As a Zodiac holder at the moment, the climb to go from Zenith > Atma > Animus > Novus > Nexus > Zodiac, while individually much easier than in the past, in sum is still a monumentous task. Is it worth it? As others have stated, the Zodiac will keep growing. The details of how have yet to be revealed, but they almost assuredly will. So, yes, having a Zodiac is worth having one, especially if it becomes more customizable, but it is my belief that come 3.0 the path to Zodiac will have to be drastically nerffed even further
Why? Because in 3.0 no one will be doing the "old content" that is required to build a Zodiac.
Relic: I'm going to just mention this to give an understanding. Guaranteed drops from 2.0 Primals. This will be old content and thus you can expect very long queue times.
Atma: Fates are here to stay, but the Atma Fates pop in specific 2.0 zones, which will not be as popular (hell even Golden Saucer may see the world empty).
Animus: More 2.0 Fates, 2.0 Dungeon Bosses, and 2.0 open world grinding.
Novus: Materia, Grades 1-4. This step can theoretically doable in 3.0 content, but remember how Spirit Bonding vs Monster level works. Grade 5 materia anyone?
Nexus: Light farming can still be done in 3.0 here as well, so this step may go unchanged.
Zodiac: This is the big one here. It requires chance drops from 2.0 - 2.4 dungeons that will most likely be deserted. Couple long queue times with low drop rates and you have a nightmare step here.
Basically, they will have to change how the Relic process upgrades for 3.0 for new players as most of the old systems will be extremely tedious. Therefore, if you still have not done your Atma, I would suggest waiting for 3.0 and just getting Shiva or Poetic weapons for now.