Are cameras using AA batteries dying or manufactures are keen to get us to spend more on some proprietary battery? Or are proprietary batteries better compared to AA? At least if I'm not using my camera with my rechargeable eneloop's could be used in a range of other devices if they are not used in the camera.
It's a combination. Proprietary battery, plus a li-ion battery can be smaller and possibly lighter than 4 AAs and definitely lasting longer than 2 AAs. The trend is for smaller, lighter cameras.
"Smaller, lighter." Exactly. Many P&S cameras are using proprietary batteries because it allows them the freedom to reduce the size of the camera and us a space that might be oddly shape. If they use AA batteries, the batteries dictate the size of the camera. Even though a fair number of cameras have a shorter battery life than the older AA powered one most of the buyers like the size of the camera.
The Eneloops and other "pre-charged" AA batteries are a vast improvement over the older NiMH AAs, but the lithium ions are better yet.