I'm far less concerned about the Klingon change in foreheads, than in tossing into the garbage the concept of Romulans as ancient Rome in the future. It was far more compelling.
Romulans were originally the noble villains. The Klingons in TNG became some bizarre notion of Samurai, with more than a little fascism thrown in. I'm not a great fan (to say the least) of Trek
novelist Diane Carey -- she grafted a lot of proto-Tea Party politics onto TOS -- but she at least had the good sense to note of a miltary that advances through assassination to write, "And we made peace with that