Don't know what you guys are talking about. CPAs seem deadly as ever to me. The other day I got hit by a CPA wave of 3500+ which on top of the 2000 wave was positively devastating
That's the only time they're dangerous, though, when they arrive right on top of a wave. I suppose if you had an incredibly confined frontier (if you were playing a snake map or the like, though it's always seemed to me that snake maps kind of break the game) they'd pack a real whallop, but spread over a large number of systems they're pretty easy to manage (much moreso than the aforementioned waves).
My experience has been quite the opposite. Normal waves are fairly easy to handle, but CPAs are the scariest. Maybe I just don't have enough CC, but 3,500 units spread across 5 planets (chokepoints) is much tougher to handle than 2000 units against 1 or 2. In addition, the waves don't have to arrive "right on top of them", if the waves come within a few minutes before or after (this is common in my experience), it still makes CPAs fairly difficult (they're difficult enough) to handle.
Another problem with CPAs is the time factor. At least on hard, you simply don't have the luxury of time to take your entire mobile fleet and spread them across 5 locations (once again chokepoints) in preparation for the oncoming attack. Since you get a warning of about 12 minutes, you can usually use the first 7 or so to do what you need in the galaxy, but what are you going to do in 7 minutes? When that CPA warning arrives, I get on edge because I'm afraid if I use my fleet for assaulting enemy planets, I won't make it home in time to be ready for the attack, and there's not much you can do in ~7 minutes anyway. When you see a CPA, you are more or less "grounded" in your base for a good 15 minutes or more, usually more because you have to rebuild your base and fend off waves, making it 30 minutes or greater before you finally are ready to go on the offensive again. 30 minutes of time lost on hard mode, especially late game where they are building carriers and such, translates into a much harder time than before. And since CPAs seem to ALWAYS hit me when I'm attacking or about to attack an AI homeworld, 30+ minutes of reinforcement on that planet is
such a bad, bad thing.