AA batteries no longer the trend?

I have a Canon S3 IS which is very good considering its an ultra zoom, takes good pictures, has a stereo mic. Only problem it has a lower res video setting. I spend more of my time using the camera as a makeshift video camera and taking pics on the fly. I wanted to upgrade to the newest canon SX40 HS but it does not use AA batteries instead some Li-on battery. I've used the camera search function on dpreview's website and it seems that there is no camera with fully articulated LCD, single lens which uses AA.

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.

The reason I don't use a proper dSLR, is because:
a) my workplace has good dSLR's but...

b). I hate carrying a huge beg full of lenses. Already I see my smartphone replacing a lot of my candid photo takes. Hopefully someone figures out why we are not getting the Altek Leo phone soon.