I feel like you may be missing the nuance in my complaint. I don't EXPECT bundled games to come with all the DLC. That's been common practice for quite a while now. Everyone knows that, so pointing it out isn't helpful.
I was not happy with the way one product was advertised and another was sold.
Calling it "jumping the gun" to look at the advertisement and the game being advertised is utterly ridiculous. How can you justify placing the blame on the consumer that sees the advertised item, looks at the item on the hosting storefront, takes no action to decline... only to discover it has changed and you have been charged.
Let's hope they noticed, right? Let's hope that when they redeem the game as "Ultimate Edition" they just somehow know and are okay with that, right? Go read the Steam forums where people are wondering where the DLC is.
I was lucky. I noticed the conversation here and unsubscribed. HAD I NOT UNSUBSCRIBED AT THAT POINT I WOULD HAVE BEEN CHARGED AUTOMATICALLY FOR SOMETHING THAT WAS NOT AS ADVERTISED. Do you not understand that?
-Email comes out.
-Person looks at games in bundle
-Person is autocharged
Whoops, game changed.
I personally don't give a flying

since I unsubscribed based on information I found here and on Steam DB. You say that everyone has a full month to decide, but how about those that decided right then and there that they wanted the bundle and permitted the autocharge? Should someone be required to keep checking in daily to see if the agreement changed? Should you be required to spend the month talking to people about it in case they had news?
That's silly.
My second complaint is not so much about Humble's handling of this situation as it is a complaint about the practice of (not) marking down DLC. All too often a publisher will discount an "ultimate" edition and not the DLC. meaning bundles potentially present a dead end or at least a very expensive pathway towards owning the complete content.
If everyone is upfront about it -- cool. I can make a decision. If we get into chopping content specifically to troll bundle buyers, well then I reserve the right to complain. It certainly isn't the end of the world, but it's worth a post or two on the internet to get it off my chest.