I'm sorry, but how can this possibly be a good thing? Why is it unreasonable for people to want different styles of jobs that cater to their preferences or playstyles?
And to your other point, YES they really can just revert the Umbral Ice change. When Shadowbringers launched, many Scholars were very unhappy with the removal of Energy Drain, and it was readded in response to the feedback before the launch of the first raid tier. The trailer/media tour builds are often 3-4 months out of date as well (as evidenced by discrepancies between SHB media tour NIN and release, or EW media tour and BRD). They are still willing and able to make changes to jobs on short notice. And the systems for either reverting the MP change are either already in place as we have currently, or can be adapted (the list of spells that restore MP under Umbral Ice can be expanded). We are not asking for them to throw out all of the work that they have done on new spells or the job gauge, but we would like them to be considerate of how these may impact the existing playerbase's enjoyment of the job and either tweak them or reach some area of compromise so that the job retains it's identity and feel.
I think it was a mistake in my initial post not to emphasise that the change to Umbral Ice would have the most significantly negative impact, and fixing it certainly does fall under "minor tweaks" as the functionality already exists. I am willing to wait for more information on the other points, but this is by far the most important thing for them to reconsider. We can adapt to the other things, but as it is the Umbral Ice change alone would significantly lower the enjoyment of the job in many player's eyes. It is entirely possible that this was an oversight, and they did truly believe that it would be an improvement for everyone, but if it is specifically to kill non-standard play then it is incredibly disingenous for them to dress it up as QoL.