Kinda selling Bismarck X short here, since there are mechanics the party has to be aware of. That they do not immediately kill you doesn't not make it a mechanic.

That said, "challenging to execute" as stated in the title doesn't always translate into a fun experience either. Pushing phases at the wrong time, latency, or just a unique combination of boss mechanics that ensure the party's death are things that can arise from making the execution more difficult.

Alexander nm was designed for a different audience than Alexander savage. If said people find friends and connect with others to get involved in Alex savage, more power to them, but an Alex NM that still had the clear rates as, say, final coil on release wouldn't be delivering on what was expected for the content.
Now more casual fcs and statics can both enjoy the story with their members and, if they feel up to it, take the steps needed for savage. Less stepping on toes for everyone.