I can see it being an experiment from their side.
They have all the usage data from the game, so maybe things aren't as we are expecting them to be.
Honestly speaking, I can't imagine this game getting 1st place among DMM games multiple times if there would be no new gamers joining the ranks.
Additionally, these are not the times of Lavender's event where 3-medaling a stage needed both a good party and the blessing of RNG.
The stage is pretty much a fork, allowing one to concentrate all his forces on one side and leave the other to a powerful ally.
The event itself offers variants for lower level players, though I can't say how that goes in practice.

Whether I like it though, it's hard to say at this point.
I like to take my time to read the story, however it takes quite a lot of it - because kanji. Thanks to the divide I don't need to hunt them in the album afterwards.
As for the single event stage, I'm not sure. I usually switched to the lower stamina ones once I'm done with the event rewards and now that would be impossible, which is a downside. Other than time, I guess time will tell.