Raekwon, Eightball & MJG, Nas, Scarface, Redman Just to name a few examples of legendary emcees who have pretty much held the same musical identity their entire careers and it hasn't hurt anything. Some guys manage to make dope music without being overly-experimental. Everybody's style isn't tailored to multiple musical lanes.
those guys are all very creative in other ways within their own lane or musical box. Nas is extremely creative with storytelling (Rewind, Undying Love etc), Raekwon has the slang and all that shyt, Redman has crazy flows, funny punchlines, great skits and wild stories, Face has a deep emotional introspective look into the human psyche, Ball & G had a brand new look & sound on that pimp shyt, storytelling was also a big part of 8Ball's creativity.
"creativity" doesn't have to mean trying EVERY style of music or trying to cram so many styles into one album or song. it doesn't mean you have to be OutKast or Wyclef or Kanye, you can have lots of creativity within your lane.
edit: plus creativity doesn't equal GOOD, sometimes it's just wack