No codex creep? Tell that to a Dark Angel player...
Codex: Dark Angels was written during 4th edition. Naturally it isn't going to work all that well in 5th. Even Daemons, the last Codex published during 4th came out sucks in 5th.
or better yet explain to me why Space puppies get a Libby that's cheaper and has more options than a standard codex chapter, without even comparing the powers. Its not cuz of the fluff, because SW hate psykers.
First, Rune Priests cost the same as Codex Librarians (or Blood Angel Librarians, for that matter). Secondly, Rune Priest psychic powers aren't better, they're different. Codex Marine psychic powers are more about supporting other units than just outright killing stuff. In fact, the Blood Angels have the most "killy" psychic powers out of the 5th edition batch (though that's sort of another topic). Null Zone is fantastic, as is Gate to Infinity and Machine Curse. Space Wolves get Living Lightning (which is great), Jaws (which is awesome against some armies and worthless against others) and Murderous Hurricane (as Jaws).
Codex creep is still there, they are just doing a better job of letting you play out of a codex several different ways instead of getting one good build out of each.
Just because a Codex can support multiple builds... wait, what? This isn't even the same thing. A Codex that can support multiple builds isn't necessarily more powerful than one that's a mono-build... okay, I can't even formulate a response to the quoted idea as it doesn't even make sense.