I see what you're getting at, but some of your examples don't help your case.
Whenever someone refers to something being "obvious" it can always boil down to a philosophical question of what obvious actually means. Nothing is truly obvious, and we've obviously conditioned from our surroundings. While we've obviously adopted conventions to interact with computers, they've offered affordances (or forced us) that hint at a function.
Gestures in general offer a challenge from a human factors perspective. Gestures can be very convenient and compelling sources of interaction that can enhance UX. Unfortunately, users are working in flatland, with very little affordances. The biggest problem here and with gestural interfaces in general is the lack of hints they give to an interaction. A physical button has a clear affordance (you can argue this is conditioned/learned) baked into the interface. There are also many issues related to the lack of universal gestures within and across applications and operating systems.
In a lot of cases, Gestures are like keyboard shortcuts. Many people discover them because they are told about them (ie. CTRL+C in the copy interface), but physically trying many different keyboard combinations just isn't something people do.
Apple has recognized the problem with gestures while pushing hard to make them standard. They still keep the home button on the iPad, even with system wide gestures that can accomplish the same thing. Overall, I agree with your sentiment that particular interactions join the ranks of some ubiquitious interactions you noted, but it will take more than a few months of use from one particular operating system and there are many challenges, no matter how convenient it is.