It is rather dumb to remove existing content. If you do not like it then do not play it more than you have to. I got my Railjack only after DE retroactively locked me out of Arbitrations. While annoying, hardly a big deal.
What would be a decent argument would for instance be "Railjack confuses new players, move it further down the progress line before they encounter it." Not that I believe that statement to be true. Just an example.
This is the only thing listed that I find valid.