What is the point of taking more than 1 level of change? Higher monster variety?
Change is for spam it off cd for jackpot chance.
The monster come from change is completely random.
example You can change level 200 monster to level 201 Hanaming.
level 1 is enuf
What is the point of having more than 1 level then?
There isn’t really one. It’s actually bad to take more than 1 if you are looking to summon something specific (wider range of mobs you can summon = lower chance you will summon the exact one you want) 
It’s much more beneficial to spend your points on the other skills.
Edit: In fact after more testing on level 1 mobs… it seems you can get any monster in the database (but it will be transformed to the same level as what you’re using the skill on). Not sure if this is a bug (I think so)