Why are Nicky's lyrics in the EMG, TIMT and KYE eras his best?

[Europa Gluten Free]

Listening back to these eras recently, I really think that these were his best. Of course all the social-history lyrics brought them success, but I especially like all the neurotic lyrics of these times (Mr Carbohydrate, The Convalescent, Prologue etc). Did the weight of success following EMG and TIMT just weigh too heavily? Did he get to self-conscious and self-critical?