CMA is not the only way, you can use the same way PS3 as well and some file can be normally "downloaded" to Vita via web browser, also pictures could be sent and received via messages plus also sent via Twitter app.
CMA doesn't need to be connected all the time, just during the initial "handshaking" between Vita and PC, just for a second or two, after that you can again cut off the internet connection. This is usefull when you're planning to transfer a large amount of data and while out and about don't want to spend money or bandwith on 3G etc.
And finally - all this Sony's fail with CMA and DRM "spying" has one BIG benefit - PC is much less protected against hacking and poking around than PS3 or Vita which allows us to have a good look in the inners of CMA and it's communication with both Vita as well as Sony servers. We can analyze the app itself, capture and monitor (and hopefully later on amend or emulate) both IP as well as USB communications which can lead to various benefits like unoficial CMAs or CMAs running on alternative platforms (MAC, Linux etc.) and much MUCH more ...
There is always light at the end of the tunnel!
Incorrent and incorrect again.