Though the LCD-2 rev1 and rev2 have almost identical frequency response charts, the new drivers change the character of the LCD-2 in a way that the graphs may not reflect i.e. they may not reflect the materials and type of the driver, which could affect the timbre and tone of the sound the headphone creates. That, and other factors*, can contribute to the enjoyment of a headphone.
There are good and bad things about everything in life let alone every headphone, and it's OK if the LCD-2 doesn't sound right to you.
I wish you health to enjoy the headphones you have, that you find headphones you enjoy, and that you enjoy the process of your life.