The problem I have (well not exactly a problem) is the low rarity has basic SD model compare to how lively the 5* and 6* girls usually have. The newer has even more diverse and flashy model too. I even hope that they will implement new SD for awakened and bloomed form and you can change them around freely too. But I guess they have enough work for design 4 new girls every 2 weeks as is.
About how OP the growth system is like I said, result of power creep. Not exactly what you can fix easily with newer and harder event right?