(1) If you want DOWNLOADABLE content then NONE of these contents with 720p and 1080p comes with AC3 and DTS. Even "HD" is kind of "fake" HD when you talk about bit rate. Compare the video quality of a bluray movie with a HD movie downloaded from netflix or itunes --- and there is a huge difference in terms of picture quality because the bit rate is massively larger in the bluray content.
(2) NONE of the handset/tablet makers paid for AC3 licensing (they including RIM all paid for AAC licensing). And Dice Player certainly didn't.
(3) If you want just a little portable movie viewer then just buy a portable dvd player with LCD screen.