From what I can piece, having played with MTool, the easyness is by design:
* The priest Akiyama tells you that 30 is the soft cap level in terms of faith and prayer power, and that it is sufficient to tackle most of the content
* The level drain is more-or-less a slap on the wrist, compared to the first game: no instant game over without Indulgence, no heavy stat penalty, Accident events take a longer time to appear, etc.
* Talking to the priest and spending a day allows you to collect 30 000 XP and recover 5 to 10 levels
* There's no time limit (explicit time limit at least), so you can just farm XP with the priest, and ressources/sidequests in the dungeons
* Once you unlock the hotel, you can use the Death Indulgence to drain your levels with the monster girls and adjust your level
So it seems that the game is made to be easy by default, so that you can unlock the gallery and replay the battles there. However, considering how you can recover to level 30 pretty quickly, it also encourages you to let yourself be drained and set your own challenge.
With that being said, when fighting, the "purify" option is grayed out, and stated to unlock after completing the game once. So I suspect that the "New Game +" of the game will be harder in some way, and perhaps at a steer cost for the protagonist, OFF style ("Purification in progress...").