Its not codex creep, its just the usual uneven codex construction. Compare csm or DA to tau, eldar, or daemons. They're hardly equivalent. Its the same as 5th really.
You are still ignoring the facts. This isn't uneven codex construction, usual or otherwise.
For one, Grey Knights, Necrons, Dark Angels, and Chaos are all competing with greater volume, and with even better results than Tau or Eldar. Daemons have mostly been used as allies to Chaos Space Marines. None of those books are imbalanced in the field of 6th edition.
5th edition was, quite honestly, the worst edition in the game's history. It was about 5-man squads and transports. You delivered a meltagun, and that was the whole game. Grey Knights threw everybody for a loop, because they could shoot, fight, and defend better than every army in the game. The 6th edition BRB launches, and suddenly they made sense (and were brought more in line with the other new 'dexes).
I know for a fact few people are actually experiencing and/or researching this, and just instead sticking to the old anti-GW diatribes. I went through the same discussion with an entire group of people at GenCon. The arguments are old, and just don't apply anymore.
"GW sucks."
"Oh yeah? Why's that?"
"They don't understand balance."
"What do you mean? In 6th edition, the top 8 of every major event has had an average of 6 different armies represented."
"Yeah but..." (the first sign of an unintelligent argument) "...what they did with Grey Knights?"
"Grey Knights are strong, but pretty much middle of the pack now. They were absurd at the end of 5th, but we see now that their rules were designed for 6th."
"But GW doesn't release stuff fast enough."
"We've had a new army for each system every single month for a year. Apocalypse being pretty much the lone exception; new models every month as well."
"But how long will I have to wait for my army?"
"What do you play?"
"Tyranids."
"Likely no later than March then, according to rumors. Either way, we will have 3 more 40k armies in that time span, no matter which it is."
"Well, what about Sisters of Battle?"
"What about them?"
"GW is screwing those players!"
"Are they stealing from them?"
"Well no."
"Then how are people being 'screwed,' as you put it?"
"How long will those players have to wait to finally get new stuff, huh, smart ass?"
"Given that they need an entire range of models in plastic, their FO greatly expanded...I'd say it will be awhile until they are done correctly. Isn't that the important thing? Plus, at the current release rate, even if Sisters were last, you're waiting until 2015, tops."
"Psh..."
I probably had these conversations three dozen times between Adepticon, Games Day, and GenCon. Same with the "codex creep," or "uneven design/newer is always better" mantra. It's people who are either uninformed, or stuck in the past when GW dropped the ball somewhere.
They've pretty much done nothing but improve in every aspect of their business, start-up cost excepting, and I can't imagine they will suddenly stop that now.
The new books aren't stronger than the ones that first came out for this edition, because GW started them all at the same time (or so Jervis Johnson, Jeremy Vetock, and Phil Kelly told me). The authors finishing off the new ones weren't even allowed to proceed without consulting the primary authors of the ones already finished.
Brass Angel, Again, the problem isn't the performance of the CSM dex if you take the best build. It is the fact that, like Tyranids, it's best build relies heavily on a subset of the codex and predominantly one specific unit. Without that one specific unit it is severly hobbled. Using the weaker half of the codex results in a crippled list. You seem to understand why Tyranids so desperately need a new codex despite our healthy performance at the highest levels. Why can you not see that the CSM codex suffers the same problems.
As for release date, I'm not putting my money down on either November or early next year. Both seem plausible to me. I don't expect the Tyranid codex any later than early next year though.
But that's not true either. At Adepticon there were Chaos lists in the quarterfinals performing without Helldrakes. There were Kharn-based lists even winning. Some people mash Daemons and CSM together. No one ever observes, verifies, or proves the alleged weaknesses of the book. They just regurgitate what people online are saying. It's mostly CSM players complaining about anything and everything another army gets that even remotely mimics something of theirs. Besides, Chaos has a MASSIVE slew of Supplements coming to flesh out their factions. That was GW's design all along: give us the book to represent a generic Chaos Warband, and flesh out the Legions with Supplements. The vanilla Space Marines book will function the same way.
Tyranids have problems, not just from being mono-build, but from being completely reliant on a subset of psychic powers from the BRB. Opposing players know too easily how to disrupt Tyranids, and we are forced to fill in points with units that would be completely unplayable under any other circumstance. They aren't experiencing a lot of success, except in tournaments with really shady scoring systems that allow for lots of comp, sportsmanship, etc. Or it will be one good Tyranids player, with everyone else going 0-2 drop.