From the Live Letter today it sounds like they might finally be "fixing" this in 4.2:

Quote 引用元：Bayohne 投稿を閲覧
We'll be making adjustments to the main scenario dungeons, so that new players can enjoy them without worrying. It may extend the duration of the dungeon; however, we have increased the rewards as well.
The way I personally read that though is that they'll be forcing cutscenes on everyone (extend the duration of the dungeon) so I have to wonder if it'll just stop people wanting to run it at all unless the rewards are insanely good... the cutscenes are so long...